Context sensitive dynamic authentication in a cryptographic system

ABSTRACT

A system for performing authentication of a first user to a second user includes the ability for the first user to submit multiple instances of authentication data which are evaluated and then used to generate an overall level of confidence in the claimed identity of the first user. The individual authentication instances are evaluated based upon: the degree of match between the user provided by the first user during the authentication and the data provided by the first user during his enrollment; the inherent reliability of the authentication technique being used; the circumstances surrounding the generation of the authentication data by the first user; and the circumstances surrounding the generation of the enrollment data by the first user. This confidence level is compared with a required trust level which is based at least in part upon the requirements of the second user, and the authentication result is based upon this comparison.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/540,030, filed Jul. 2, 2012, which is a continuation of U.S.patent application Ser. No. 12/878,317, filed Sep. 9, 2010, now U.S.Pat. No. 8,214,650, which is a continuation of U.S. patent applicationSer. No. 11/839,927, filed Aug. 16, 2007, now U.S. Pat. No. 7,802,104,which is a continuation of U.S. patent application Ser. No. 09/666,377,filed Sep. 20, 2000, now U.S. Pat. No. 7,260,724, which claims prioritybenefit under 35 U.S.C. 119(e) from U.S. Provisional Patent ApplicationNo. 60/154,734, filed Sep. 20, 1999, entitled “SECURE SITE FOR INTERNETTRANSACTIONS” and from U.S. Provisional Application No. 60/200,396,filed Apr. 27, 2000, entitled “SECURE SITE FOR INTERNET TRANSACTIONS.”The contents of U.S. patent application Ser. Nos. 13/540,030,12/878,317, 11/839,927, 09/666,377, 60/154,734, and 60/200,396 arehereby incorporated by reference herein.

FIELD OF THE INVENTION

The field relates to cryptographic authentication. More specifically,the field relates to the evaluation of an authentication event basedupon the context of that event.

DESCRIPTION OF THE RELATED ART

With the continued increase in commercial and other transactions takingplace across linked computer systems, it has become desirable to securethese transactions and the information related to these transactions.One form of security is to prevent access to systems which performcertain functions, for instance by requiring a password or PIN number inorder to use an ATM. Another form of security is to protect data frombeing intercepted and used by those other than the intended recipients,for instance, when sending a credit card number electronically. Anotherform of security involves allowing someone to undeniably sign a documentor otherwise assent to a transaction electronically.

All of these functions are related to the concept of authentication, orproof of identity. Authentication of electronic systems, particularlydigital systems, is generally carried out using cryptographic techniquesand protocols. Cryptography is the scrambling of information in such aspecific way that it can only be unscrambled by someone who holds theappropriate unscrambling key. By exchanging messages which can only bedecrypted by those with access to the proper key, cryptographicprotocols can be used as a means to authenticate individuals.

Techniques of authentication vary in their ease of use and theirreliability. For instance, a classical authentication technique in bothelectronic and non-electronic systems is the password. Anyone who knowsthe password for the club is assumed to be a member and is admitted.Anyone who doesn't know the password is prohibited. Similarly, someonewho knows a particular individual's password is assumed to be thatindividual, while someone who doesn't is assumed to be someone else.

This technique is fairly simple to implement, and fairly simple to use.The individuals being authenticated need merely remember the password,and they can be authenticated by anyone else who knows the password.However, such a technique is also fairly unreliable; people may beforget their own password or overhear someone else's password.

Other techniques for authentication involve the use or control of aparticular token, such as a particular key, either physical orelectronic. Still other techniques are based upon some immutablephysical characteristic of a user, such as a fingerprint or the sound oftheir voice. Some of these techniques are more reliable than others. Forinstance, fingerprints are more effective authenticators than passwordsin most cases. However, analyzing a fingerprint to determine if someoneis who they claim to be is much more complex than simply comparingpasswords. Generally, the more reliable a technique of authenticationis, the more cumbersome it is to use.

Therefore, there is a continued need for improved systems that provideappropriate levels of reliable authentication and security with theimproved ease of use and reduced inconvenience to the users.

SUMMARY

Based on the foregoing, a need exists to provide a method forauthenticating a user here the user is authenticated based on thoseaspects of his current circumstances which are most reliable for use indetermining that the user is who he says he is. Accordingly, one aspectof the invention is to provide a secure server, or trust engine, havingserver-centric keys, or in other words, storing cryptographic keys anduser authentication data on a server. According to this embodiment, auser accesses the trust engine in order to perform authentication andcryptographic functions, such as, for example, authentication,authorization, digital signing and generation, storage, and retrieval ofcertificates, encryption, notary-like and power-of-attorney-likeactions, and the like.

Another aspect of the invention is to provide a reliable, or trusted,authentication process. Moreover, subsequent to a trustworthy positiveauthentication, a wide number of differing actions may be taken, fromproviding cryptographic technology, to system or device authorizationand access, to permitting use or control of a wide number of electronicdevices.

Another aspect of the invention is to provide cryptographic keys andauthentication data in an environment where they are not lost, stolen,or compromised, thereby advantageously avoiding a need to continuallyreissue and manage new keys and authentication data. According toanother aspect of the invention, the trust engine allows a user to useone key pair for multiple activities, vendors, and/or authenticationrequests.

According to yet another aspect of the invention, the trust engineperforms the majority of cryptographic processing, such as encrypting,authenticating, or signing, on the server side, thereby allowing clientsto possess only minimal computing resources. According to yet anotheraspect of the invention, the trust engine includes multiple depositoriesfor storing portions of each cryptographic key and authentication data.The portions are created through a data splitting process that prohibitsreconstruction without a predetermined portion from more than onedepository. According to another embodiment, the multiple depositoriesare geographically remote such that a rogue employee or otherwisecompromised system at one depository will not provide access to a user'skey or authentication data.

According to yet another aspect, the authentication processadvantageously allows the trust engine to process vendor and userauthentication activities in parallel. According to yet anotherembodiment, the trust engine may advantageously track failed accessattempts and thereby limit the number of times malicious intruders mayattempt to subvert the system.

According to yet another aspect, the trust engine may include multipleinstantiations where each trust engine may predict and share processingloads with the others. According to yet another embodiment, the trustengine may include a redundancy module for polling a plurality ofauthentication results to ensure that more than one system authenticatesthe user.

Therefore, one embodiment of the invention provides a method where datais obtained from the user during an authentication attempt along withdata describing one or more aspects of the current circumstancessurrounding the authentication attempt. This data is compared topreviously received data associated with the circumstances of theprevious authentication attempts by this user. Based upon thiscomparison, a level of trust for the authentication attempt of the user.

According to another aspect of the invention, a method forauthenticating a user is provided in which authentication data isobtained associated with an authentication operation, and metadata isobtained related to the authentication operation. This metadata iscompared with data which has previously been received and a level oftrust associated with the authentication operation is determined.

According to yet another aspect of the invention, the authenticationdata is comprised of data generated using more than one authenticationtechnique. Data generated using different techniques is compared withdifferent portions of the set of previously stored data in order todetermine a level of trust for the authentication.

An additional aspect of the invention provides a system for gradedauthentication comprising user data and circumstantial data used by atrust engine. The user data is obtained from a user during previouslysuccessful authentication attempts, and circumstantial data associatedwith these previously successful authentication attempts is alsoreceived. The trust engine generates a level of trust associated with acurrent authentication attempt by comparing circumstantial dataassociated with the current authentication attempt with thecircumstantial data associated with the previously successfulauthentication attempts.

In another embodiment of the invention, a method for grading anauthentication operation is relying on a variable set of authenticationtechniques used to obtain authentication data is provided. Thereliability of the set of authentication techniques available isdefined, and authentication data is received during an authenticationoperation. The authentication data is generated using a subset of theavailable authentication techniques. The acceptability of theauthentication data is determined for the subset of data generated byeach of the techniques used, and the level of trust is defined for theauthentication operation based upon the acceptability the authenticationdata and the reliability of the authentication techniques used togenerated the authentication data.

Yet another aspect of the invention provides an apparatus for evaluatingan authentication attempt. The apparatus comprises reliability datawhich is associated with a set of authentication techniques that may beused in an authentication attempt. It also comprises a plurality ofauthentication instances generated using a subset of the authenticationtechniques. A trust engine determines a level of match associated witheach authentication instance. These levels of match are used to assign alevel of trust for the authentication attempt. The level of trust isdetermined by the level of match associated with each authenticationinstance and the reliability of the technique used in eachauthentication instance.

According to yet another aspect of the invention, a method for gradingan authentication attempt is provided in which the reliability of a setof authentication techniques that may be used in an authenticationattempt is defined. A plurality of authentication instances generatedusing a subset of these authentication techniques is then received and alevel of match is associated with each authentication instance. Thelevel of trust of the authentication attempt is then defined based uponthe level of match associated with each authentication instance and uponthe reliability of the technique used in each authentication instance.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in more detail below in connectionwith the attached drawings, which are meant to illustrate and not tolimit the invention, and in which:

FIG. 1 illustrates a block diagram of a cryptographic system, accordingto aspects of an embodiment of 5 the invention;

FIG. 2 illustrates a block diagram of the trust engine of FIG. 1,according to aspects of an embodiment of the invention;

FIG. 3 illustrates a block diagram of the transaction engine of FIG. 2,according to aspects of an embodiment of the invention;

FIG. 4 illustrates a block diagram of the depository of FIG. 2,according to aspects of an embodiment of the invention;

FIG. 5 illustrates a block diagram of the authentication engine of FIG.2, according to aspects of an embodiment of the invention;

FIG. 6 illustrates a block diagram of the cryptographic engine of FIG.2, according to aspects of an 15 embodiment of the invention;

FIG. 7 illustrates a block diagram of a depository system, according toaspects of another embodiment of the invention;

FIG. 8 illustrates a flow chart of a data splitting process according toaspects of an embodiment of the invention;

FIG. 9A illustrates a data flow of an enrollment process according toaspects of an embodiment of the invention;

FIG. 9B illustrates a flow chart of an interoperability processaccording to aspects of an embodiment of the invention;

FIG. 10 illustrates a data flow of an authentication process accordingto aspects of an embodiment of the invention;

FIG. 11 illustrates a data flow of a signing process according toaspects of an embodiment of the invention;

FIG. 12 illustrates a data flow and an encryption/decryption processaccording to aspects and yet another embodiment of the invention;

FIG. 13 illustrates a simplified block diagram of a trust engine systemaccording to aspects of another embodiment of the invention;

FIG. 14 illustrates a simplified block diagram of a trust engine systemaccording to aspects of another embodiment of the invention;

FIG. 15 illustrates a block diagram of the redundancy module of FIG. 14,according to aspects of an embodiment of the invention;

FIG. 16 illustrates a process for evaluating authentications accordingto one aspect of the invention;

FIG. 17 illustrates a process for assigning a value to an authenticationaccording to one aspect as shown in FIGURE, 16 of the invention;

FIG. 18 illustrates a process for performing trust arbitrage in anaspect of the invention as shown in FIG. 17;

FIG. 19 illustrates a sample transaction between a user and a vendoraccording to aspects of an embodiment of the invention where an initialweb based contact leads to a sales contract signed by both parties.

FIG. 20 illustrates a sample user system with a cryptographic serviceprovider module which provides security functions to a user system.

DETAILED DESCRIPTION OF EMBODIMENTS

One aspect of the present invention is to provide a cryptographic systemwhere one or more secure servers, or a trust engine, storescryptographic keys and user authentication data. Users access thefunctionality of conventional cryptographic systems through networkaccess to the trust engine, however, the trust engine does not releaseactual keys and other authentication data and therefore, the keys anddata remain secure. This server-centric storage of keys andauthentication data provides for user-independent security, portability,availability, and straightforwardness.

Because users can be confident in, or trust, the cryptographic system toperform user and document authentication and other cryptographicfunctions, a wide variety of functionality may be incorporated into thesystem. For example, the trust engine provider can ensure againstagreement repudiation by, for example, authenticating the agreementparticipants, digitally signing the agreement on behalf of or for theparticipants, and storing a record of the agreement digitally signed byeach participant. In addition, the cryptographic system may monitoragreements and determine to apply varying degrees of authentication,based on, for example, price, user, vendor, geographic location, placeof use, or the like.

To facilitate a complete understanding of the invention, the remainderof the detailed description describes the invention with reference tothe figures, wherein like elements are referenced with like numeralsthroughout.

FIG. 1 illustrates a block diagram of a cryptographic system 100,according to aspects of an embodiment of the invention. As shown in FIG.1, the cryptographic system 100 includes a user system 105, a trustengine 110, a certificate authority 115, and a vendor system 120,communicating through a communication link 125.

According to one embodiment of the invention, the user system 105comprises a conventional general-purpose computer having one or moremicroprocessors, such as, for example, an Intel-based processor.Moreover, the user system 105 includes an appropriate operating system,such as, for example, an operating system capable of including graphicsor windows, such as Windows, Unix, Linux, or the like. As shown in FIG.1, the user system 105 may include a biometric device 107. The biometricdevice 107 may advantageously capture a user's biometric and transferthe captured biometric to the trust engine 110. According to oneembodiment of the invention, the biometric 35 device may advantageouslycomprise a device having attributes and features similar to thosedisclosed in U.S. patent application Ser. No. 08/926,277, filed on Sep.5, 1997, entitled “RELIEF OBJECT IMAGE GENERATOR,” U.S. patentapplication Ser. No. 09/558,634, filed on Apr. 26, 2000, entitled“IMAGING DEVICE FOR A RELIEF OBJECT AND SYSTEM AND METHOD OF USING THEIMAGE DEVICE, U.S. patent application Ser. No. 09/435,011, filed on Nov.5, 1999, entitled “RELIEF OBJECT SENSOR ADAPTOR,” and U.S. patentapplication Ser. No. 09/477,943, filed on Jan. 5, 2000, entitled “PLANAROPTICAL IMAGE SENSOR AND SYSTEM FOR GENERATING AN ELECTRONIC IMAGE OF ARELIEF OBJECT FOR FINGERPRINT READING,” all of which are owned by theinstant assignee, and all of which are hereby incorporated by referenceherein.

In addition, the user system 105 may connect to the communication link125 through a conventional service provider, such as, for example, adial up, digital subscriber line (DSL), cable modem, fiber connection,or the like. According to another embodiment, the user system 105connects the communication link 125 through network connectivity suchas, for example, a local or wide area network. According to oneembodiment, the operating system includes a TCP/IP stack that handlesall incoming and outgoing message traffic passed over the communicationlink 125.

Although the user system 105 is disclosed with reference to theforegoing embodiments, the invention is not intended to be limitedthereby. Rather, a skilled artisan will recognize from the disclosureherein, a wide number of alternatives embodiments of the user system105, including almost any computing device capable of sending orreceiving information from another computer system. For example, theuser system 105 may include a computer workstation, an interactivetelevision, an interactive kiosk, a personal mobile computing device,such as a digital assistant, mobile phone, laptop, or the like, awireless communications device, a smartcard, an embedded computingdevice, or the like, which can interact with the communication link 125.In such alternative systems, the operating systems will likely differand be adapted for the particular device. However, according to oneembodiment, the operating systems advantageously continue to provide theappropriate communications protocols needed to establish communicationwith the communication link 125.

FIG. 1 illustrates the trust engine 110. According to one embodiment,the trust engine 110 comprises one or more secure servers for accessingand storing sensitive information, such as user authentication data andpublic and private cryptographic keys. According to one embodiment, theauthentication data includes data designed to uniquely identify a userof the cryptographic system 100. For example, the authentication datamay include a user identification number, one or more biometrics, and aseries of questions and answers generated by the trust engine 110 or theuser, but answered initially by the user at enrollment. The foregoingquestions may include demographic data, such as place of birth, address,anniversary, or the like, personal data, such as mother's maiden name,favorite ice cream, or the like, or other data designed to uniquelyidentify the user. The trust engine 110 compares a user's authenticationdata associated with a current transaction, to the authentication dataprovided at an earlier time, such as, for example, during enrollment.The trust engine 110 may advantageously require the user to produce theauthentication data at the time of each transaction, or, the trustengine 110 may advantageously allow the user to periodically produceauthentication data, such as at the beginning of a string oftransactions or the logging onto a particular vendor website.

According to the embodiment where the user produces biometric data, theuser provides a physical characteristic, such as a fingerprint orspeech, to the biometric device 107. The biometric device advantageouslyproduces an electronic pattern, or biometric, of the physicalcharacteristic. The electronic pattern is transferred through the usersystem 105 to the trust engine 110 for either enrollment orauthentication purposes.

Once the user produces the appropriate authentication data and the trustengine 110 determines a positive match between that authentication data(current authentication data) and the authentication data provided atthe time of enrollment (enrollment authentication data), the trustengine 110 provides the user with complete cryptographic functionality.For example, the properly authenticated user may advantageously employthe trust engine 110 to perform hashing, digitally signing, encryptingand decrypting (often referred to only as encrypting), creating ordistributing digital certificates, and the like. However, the privatecryptographic keys used in the cryptographic functions will not beavailable outside the trust engine 110, thereby ensuring the integrityof the cryptographic keys.

According to one embodiment, the trust engine 110 generates and storescryptographic keys. According to another embodiment, at least onecryptographic key is associated with each user. Moreover, when thecryptographic keys include public-key technology, each private keyassociated with a user is generated within, and not released from, thetrust engine 110. Thus, so long as the user has access to the trustengine 110, the user may perform cryptographic functions using his orher private or public key. Such remote access advantageously allowsusers to remain completely mobile and access cryptographic functionalitythrough practically any Internet connection, such as cellular andsatellite phones, kiosks, laptops, hotel rooms and the like.

According to another embodiment, the trust engine 110 performs thecryptographic functionality using a key pair generated for the trustengine 110. According to this embodiment, the trust engine 110 firstauthenticates the user, and after the user has properly producedauthentication data matching the enrollment authentication data, thetrust engine 110 uses its own cryptographic key pair to performcryptographic functions on behalf of the authenticated user.

A skilled artisan will recognize from the disclosure herein that thecryptographic keys may advantageously include some or all of symmetrickeys, public keys, and private keys. In addition, a skilled artisan willrecognize from the disclosure herein that the foregoing keys may beimplemented with a wide number of algorithms available from commercialtechnologies, such as, for example, RSA, ELGAMAL, or the like.

FIG. 1 also illustrates the certificate authority 115. According to oneembodiment, the certificate authority 115 may advantageously comprise atrusted thirdparty organization or company that issues digitalcertificates, such as, for example, VeriSign, Baltimore, Entrust, or thelike. The trust engine 110 may advantageously transmit requests fordigital certificates, through one or more conventional digitalcertificate protocols, such as, for example, PKCS10, to the certificateauthority 115. In response, the certificate authority 115 will issue adigital certificate in one or more of a number of differing protocols,such as, for example, PKCS7. According to one embodiment of theinvention, the trust engine 110 requests digital certificates fromseveral or all of the prominent certificate authorities 115 such thatthe trust engine 110 has access to a digital certificate correspondingto the certificate standard of any requesting party.

According to another embodiment, the trust engine 110 internallyperforms certificate issuances. In this embodiment, the trust engine 110may access a certificate system for generating certificates and/or mayinternally generate certificates when they are requested, such as, forexample, at the time of key generation or in the certificate standardrequested at the time of the request. The trust engine 110 will bedisclosed in greater detail below.

FIG. 1 also illustrates the vendor system 120. According to oneembodiment, the vendor system 120 advantageously comprises a Web server.Typical Web servers generally serve content over the Internet using oneof several internet markup languages or document format standards, suchas the Hyper-Text Markup Language (HTML) or the Extensible MarkupLanguage (XML). The Web server accepts requests from browsers likeNetscape and Internet Explorer and then returns the appropriateelectronic documents. A number of server or client-side technologies canbe used to increase the power of the Web server beyond its ability todeliver standard electronic documents. For example, these technologiesinclude Common Gateway Interface (CGI) scripts, Secure Sockets Layer(SSL) security, and Active Server Pages (ASPs). The vendor system 120may advantageously provide electronic content relating to commercial,personal, educational, or other transactions.

Although the vendor system 120 is disclosed with reference to theforegoing embodiments, the invention is not intended to be limitedthereby. Rather, a skilled artisan will recognize from the disclosureherein that the vendor system 120 may advantageously comprise any of thedevices described with reference to the user system 105 or combinationthereof

FIG. 1 also illustrates the communication link 125 connecting the usersystem 105, the trust engine 110, the certificate authority 115, and thevendor system 120. According to one embodiment, the communication link125 preferably comprises the Internet. The Internet, as used throughoutthis disclosure is a global network of computers. The structure of theInternet, which is well known to those of ordinary skill in the art,includes a network backbone with networks branching from the backbone.These branches, in turn, have networks branching from them, and so on.Routers move information packets between network levels, and then fromnetwork to network, until the packet reaches the neighborhood of itsdestination. From the destination, the destination network's hostdirects the information packet to the appropriate terminal, or node. Inone advantageous embodiment, the Internet routing hubs comprise domainname system (DNS) servers using Transmission Control Protocol/InternetProtocol (TCP/IP) as is well known in the art. The routing hubs connectto one or more other routing hubs via high-speed communication links.

One popular part of the Internet is the World Wide Web. The World WideWeb contains different computers, which store documents capable ofdisplaying graphical and textual information. The computers that provideinformation on the World Wide Web are typically called “websites.” Awebsite is defined by an Internet address that has an associatedelectronic page. The electronic page can be identified by a UniformResource Locator (URL). Generally, an electronic page is a document thatorganizes the presentation of text, graphical images, audio, video, andso forth.

Although the communication link 125 is disclosed in terms of itspreferred embodiment, one of ordinary skill in the art will recognizefrom the disclosure herein that the communication link 125 may include awide range of interactive communications links. For example, thecommunication link 125 may include interactive television networks,telephone networks, wireless data transmission systems, two-way cablesystems, customized private or public computer networks, interactivekiosk networks, automatic teller machine networks, direct links,satellite or cellular networks, and the like.

FIG. 2 illustrates a block diagram of the trust engine 110 of FIG. 1according to aspects of an 10 embodiment of the invention. As shown inFIG. 2, the trust engine 110 includes a transaction engine 205, adepository 210, an authentication engine 215, and a cryptographic engine220. According to one embodiment of the invention, the trust engine 110also includes mass storage 225. As further shown in FIG. 2, thetransaction engine 205 communicates with the depository 210, theauthentication engine 215, and the cryptographic engine 220, along withthe mass storage 225. In addition, the depository 210 communicates withthe authentication engine 215, the cryptographic engine 220, and themass storage 225. Moreover, the authentication engine 215 communicateswith the cryptographic engine 220. According to one embodiment of theinvention, some or all of the foregoing communications mayadvantageously comprise the transmission of XML documents to IPaddresses that correspond to the receiving device. As mentioned in theforegoing, XML documents advantageously allow designers to create theirown customized document tags, enabling the definition, transmission,validation, and interpretation of data between applications and betweenorganizations. Moreover, some or all of the foregoing communications mayinclude conventional SSL technologies.

According to one embodiment, the transaction engine 205 comprises a datarouting device, such as a conventional Web server available fromNetscape, Microsoft, Apache, or the like. For example, the Web servermay advantageously receive incoming data from the communication link125. According to one embodiment of the invention, the incoming data isaddressed to a front-end security system for the trust engine 110. Forexample, the front-end security system may advantageously include afirewall, an intrusion detection system searching for known attackprofiles, and/or a virus scanner. After clearing the front-end securitysystem, the data is received by the transaction engine 205 and routed toone of the depository 210, the authentication engine 215, thecryptographic engine 220, and the mass storage 225. In addition, thetransaction engine 205 monitors incoming data from the authenticationengine 215 and cryptographic engine 220, and routes the data toparticular systems through the communication link 125. For example, thetransaction engine 205 may advantageously route data to the user system105, the certificate authority 115, or the vendor system 120.

According to one embodiment, the data is routed using conventional HTTProuting techniques, such as, for example, employing URLs or UniformResource Indicators (URLs). URLs are similar to URLs, however, URLstypically 35 indicate the source of files or actions, such as, forexample, executables, scripts, and the like. Therefore, according to theone embodiment, the user system 105, the certificate authority 115, thevendor system 120, and the components of the trust engine 210,advantageously include sufficient data within communication URLs or URLsfor the transaction engine 205 to properly route data throughout thecryptographic system.

Although the data routing is disclosed with reference to its preferredembodiment, a skilled artisan will recognize a wide number of possibledata routing solutions or strategies. For example, XML or other datapackets may advantageously be unpacked and recognized by their format,content, or the like, such that the transaction engine 205 may properlyroute data throughout the trust engine 110. Moreover, a skilled artisanwill recognize that the data routing may advantageously be adapted tothe data transfer protocols conforming to particular network systems,such as, for example, when the communication link 125 comprises a localnetwork.

According to yet another embodiment of the invention, the transactionengine 205 includes conventional SSL encryption technologies, such thatthe foregoing systems may authenticate themselves, and vise-versa, withtransaction engine 205, during particular communications. As will beused throughout this disclosure, the term “½ SSL” refers tocommunications where a server but not necessarily the client, is SSLauthenticated, and the term “FULL SSL” refers to communications wherethe client and the server are SSL authenticated. When the instantdisclosure uses the term “SSL”, the communication may comprise ½ or FULLSSL.

As the transaction engine 205 routes data to the various components ofthe cryptographic system 100, the transaction engine 205 mayadvantageously create an audit trail. According to one embodiment, theaudit trail includes a record of at least the type and format of datarouted by the transaction engine 205 throughout the cryptographic system100. Such audit data may advantageously be stored in the mass storage225.

FIG. 2 also illustrates the depository 210. According to one embodiment,the depository 210 comprises one or more data storage facilities, suchas, for example, a directory server, a database server, or the like. Asshown in FIG. 2, the depository 210 stores cryptographic keys andenrollment authentication data. The cryptographic keys mayadvantageously correspond to the trust engine 110 or to users of thecryptographic system 100, such as the user or vendor. The enrollmentauthentication data may advantageously include data designed to uniquelyidentify a user, such as, user ID, passwords, answers to questions,biometric data, or the like. This enrollment authentication data mayadvantageously be acquired at enrollment of a user or anotheralternative later time. For example, the trust engine 110 may includeperiodic or other renewal or reissue of enrollment authentication data.

According to one embodiment, the communication from the transactionengine 205 to and from the authentication engine 215 and thecryptographic engine 220 comprises secure communication, such as, forexample conventional SSL technology. In addition, as mentioned in theforegoing, the data of the communications to and from the depository 210may be transferred using URLs, URLs, HTTP or XML documents, with any ofthe foregoing advantageously having data requests and formats embeddedtherein.

As mentioned above, the depository 210 may advantageously comprises aplurality of secure data storage facilities. In such an embodiment, thesecure data storage facilities may be configured such that a compromiseof the security in one individual data storage facility will notcompromise the cryptographic keys or the authentication data storedtherein. For example, according to this embodiment, the cryptographickeys and the authentication data are mathematically operated on so as tostatistically and substantially randomize the data stored in each datastorage facility. According to one embodiment, the randomization of thedata of an individual data storage facility renders that dataundecipherable. Thus, compromise of an individual data storage facilityproduces only a randomized undecipherable number and does not compromisethe security of any cryptographic keys or the authentication data as awhole.

FIG. 2 also illustrates the trust engine 110 including theauthentication engine 215. According to one embodiment, theauthentication engine 215 comprises a data comparator configured tocompare data from the transaction engine 205 with data from thedepository 210. For example, during authentication, a user suppliescurrent authentication data to the trust engine 110 such that thetransaction engine 205 receives the current authentication data. Asmentioned in the foregoing, the transaction engine 205 recognizes thedata requests, preferably in the URL or URI, and routes theauthentication data to the authentication engine 215. Moreover, uponrequest, the depository 210 forwards enrollment authentication datacorresponding to the user to the authentication engine 215. Thus, theauthentication engine 215 has both the current authentication data andthe enrollment authentication data for comparison.

According to one embodiment, the communications to the authenticationengine comprise secure communications, such as, for example, SSLtechnology. Additionally, security can be provided within the trustengine 110 components, such as, for example, super-encryption usingpublic key technologies. For example, according to one embodiment, theuser encrypts the current authentication data with the public key of theauthentication engine 215. In addition, the depository 210 also encryptsthe enrollment authentication data with the public key of theauthentication engine 215. In this way, only the authentication engine'sprivate key can be used to decrypt the transmissions.

As shown in FIG. 2, the trust engine 110 also includes the cryptographicengine 220. According to one embodiment, the cryptographic enginecomprises a cryptographic handling module, configured to advantageouslyprovide conventional cryptographic functions, such as, for example,public-key infrastructure (PKI) functionality. For example, thecryptographic engine 220 may advantageously issue public and privatekeys for users of the cryptographic system 100. In this manner, thecryptographic keys are generated at the cryptographic engine 220 andforwarded to the depository 210 such that at least the privatecryptographic keys are not available outside of the trust engine 110.According to another embodiment, the cryptographic engine 220 randomizesand splits at least the private cryptographic key data, thereby storingonly the randomized split data. Similar to the splitting of theenrollment authentication data, the splitting process ensures the storedkeys are not available outside the cryptographic engine 220. Accordingto another embodiment, the functions of the cryptographic engine can becombined with and performed by the authentication engine 215.

According to one embodiment, communications to and from thecryptographic engine include secure communications, such as SSLtechnology. In addition, XML documents may advantageously be employed totransfer data and/or make cryptographic function requests.

FIG. 2 also illustrates the trust engine 110 having the mass storage225. As mentioned in the foregoing, the transaction engine 205 keepsdata corresponding to an audit trail and stores such data in the massstorage 225. Similarly, according to one embodiment of the invention,the depository 210 keeps data corresponding to an audit trail and storessuch data in the mass storage device 225. The depository audit traildata is similar to that of the transaction engine 205 in that the audittrail data comprises a record of the requests received by the depository210 and the response thereof. In addition, the mass storage 225 may beused to store digital certificates having the public key of a usercontained therein.

Although the trust engine 110 is disclosed with reference to itspreferred and alternative embodiments, the invention is not intended tobe limited thereby. Rather, a skilled artisan will recognize in thedisclosure herein, a wide number of alternatives for the trust engine110. For example, the trust engine 110, may advantageously perform onlyauthentication, or alternatively, only some or all of the cryptographicfunctions, such as data encryption and decryption. According to suchembodiments, one of the authentication engine 215 and the cryptographicengine 220 may advantageously be removed, thereby creating a morestraightforward design for the trust engine 110. In addition, thecryptographic engine 220 may also communicate with a certificateauthority such that the certificate authority is embodied within thetrust engine 110. According to yet another embodiment, the trust engine110 may advantageously perform authentication and one or morecryptographic functions, such as, for example, digital signing

FIG. 3 illustrates a block diagram of the transaction engine 205 of FIG.2, according to aspects of an embodiment of the invention. According tothis embodiment, the transaction engine 205 comprises an operatingsystem 305 having a handling thread and a listening thread. Theoperating system 305 may advantageously be similar to those found inconventional high volume servers, such as, for example, Web serversavailable from Apache. The listening thread monitors the incomingcommunication from one of the communication link 125, the authenticationengine 215, and the cryptographic engine 220 for incoming data flow. Thehandling thread recognizes particular data structures of the incomingdata flow, such as, for example, the foregoing data structures, therebyrouting the incoming data to one of the communication link 125, thedepository 210, the authentication engine 215, the cryptographic engine220, or the mass storage 225. As shown in FIG. 3, the incoming andoutgoing data may advantageously be secured through, for example, SSLtechnology.

FIG. 4 illustrates a block diagram of the depository 210 of FIG. 2according to aspects of an embodiment of the invention. According tothis embodiment, the depository 210 comprises one or more lightweightdirectory access protocol (LDAP) servers. LDAP directory servers areavailable from a wide variety of manufacturers such as Netscape, ISO,and others. FIG. 4 also shows that the directory server preferablystores data 405 corresponding to the cryptographic keys and data 410corresponding to the enrollment authentication data. According to oneembodiment, the depository 210 comprises a single logical memorystructure indexing authentication data and cryptographic key data to aunique user ID. The single logical memory structure preferably includesmechanisms to ensure a high degree of trust, or security, in the datastored therein. For example, the physical location of the depository 210may advantageously include a wide number of conventional securitymeasures, such as limited employee access, modern surveillance systems,and the like. In addition to, or in lieu of, the physical securities,the computer system or server may advantageously include softwaresolutions to protect the stored data. For example, the depository 210may advantageously create and store data 415 corresponding to an audittrail of actions taken. In addition, the incoming and outgoingcommunications may advantageously be encrypted with public keyencryption coupled with conventional SSL technologies.

According to another embodiment, the depository 210 may comprisedistinct and physically separated data storage facilities, as disclosedfurther with reference to FIG. 7.

FIG. 5 illustrates a block diagram of the authentication engine 215 ofFIG. 2 according to aspects of an embodiment of the invention. Similarto the transaction engine 205 of FIG. 3, the authentication engine 215comprises an operating system 505 having at least a listening and ahandling thread of a modified version of a conventional Web server, suchas, for example, Web servers available from Apache. As shown in FIG. 5,the authentication engine 215 includes access to at least one privatekey 510. The private key 510 may advantageously be used for example, todecrypt data from the transaction engine 205 or the depository 210,which was encrypted with a corresponding public key of theauthentication engine 215.

FIG. 5 also illustrates the authentication engine 215 comprising acomparator 515, a data splitting module 520, and a data assemblingmodule 525. According to the preferred embodiment of the invention, thecomparator 515 includes technology capable of comparing potentiallycomplex patterns related to the foregoing biometric authentication data.The technology may include hardware, software, or combined solutions forpattern comparisons, such as, for example, those representing fingerprint patterns or voice patterns. In addition, according to oneembodiment, the comparator 515 of the authentication engine 215 mayadvantageously compare conventional hashes of documents in order torender a comparison result. According to one embodiment of theinvention, the comparator 515 includes the application of heuristics 530to the comparison. The heuristics 530 may advantageously addresscircumstances surrounding an authentication attempt, such as, forexample, the time of day, IP address or subnet mask, purchasing profile,email address, processor serial number or ID, or the like.

Moreover, the nature of biometric data comparisons may result in varyingdegrees of confidence being produced from the matching of currentbiometric authentication data to enrollment data. For example, unlike atraditional password which may only return a positive or negative match,a fingerprint may be determined to be a partial match, e.g., a 90%match, a 75% match, or a 10% match, rather than simply being correct orincorrect. Other biometric identifiers such as voice print analysis orface recognition may share this property of probabilisticauthentication, rather than absolute authentication.

When working with such probabilistic authentication or in other caseswhere an authentication is considered less than absolutely reliable, itis desirable to apply the heuristics 530 to determine whether the levelof confidence in the authentication provided is sufficiently high toauthenticate the transaction which is being made.

It will sometimes be the case that the transaction at issue is arelatively low value transaction where it is acceptable to beauthenticated to a lower level of confidence. This could include atransaction which has a low dollar value associated with it (e.g., a $10purchase) or a transaction with low risk (e.g., admission to amembers-only web site).

Conversely, for authenticating other transactions, it may be desirableto require a high degree of confidence in the authentication beforeallowing the transaction to proceed. Such transactions may includetransactions of large dollar value (e.g., signing a multi-million dollarsupply contract) or transaction with a high risk if an improperauthentication occurs (e.g., remotely logging onto a governmentcomputer).

The use of the heuristics 530 in combination with confidence levels andtransactions values may be used as will be described below to allow thecomparator to provide a dynamic context-sensitive authentication system.

According to another embodiment of the invention, the comparator 515 mayadvantageously track authentication attempts for a particulartransaction. For example, when a transaction fails, the trust engine 110may request the user to re-enter his or her current authentication data.The comparator 515 of the authentication engine 215 may advantageouslyemploy an attempt limiter 535 to limit the number of authenticationattempts, thereby prohibiting brute-force attempts to impersonate auser's authentication data. According to one embodiment, the attemptlimiter 535 comprises a software module monitoring transactions forrepeating authentication attempts and, for example, limiting theauthentication attempts for a given transaction to three. Thus, theattempt limiter 535 will limit an automated attempt to impersonate anindividual's authentication data to, for example, simply three“guesses.” Upon three failures, the attempt limiter 535 mayadvantageously deny additional authentication attempts. Such denial mayadvantageously be implemented through, for example, the comparator 515returning a negative result regardless of the current authenticationdata being transmitted. On the other hand, the transaction engine 205may advantageously block any additional authentication attemptspertaining to a transaction in which three attempts have previouslyfailed.

The authentication engine 215 also includes the data splitting module520 and the data assembling module 525. The data splitting module 520advantageously comprises a software, hardware, or combination modulehaving the ability to mathematically operate on various data so as tosubstantially randomize and split the data into portions. According toone embodiment, original data is not recreatable from an individualportion. The data assembling module 525 advantageously comprises asoftware, hardware, or combination module configured to mathematicallyoperate on the foregoing substantially randomized portions, such thatthe combination thereof provides the original deciphered data. Accordingto one embodiment, the authentication engine 215 employs the datasplitting module 520 to randomize and split enrollment authenticationdata into portions, and employs the data assembling module 525 toreassemble the portions into usable enrollment authentication data.

FIG. 6 illustrates a block diagram of the cryptographic engine 220 ofthe trust engine 200 of FIG. 2 according to aspects of one embodiment ofthe invention. Similar to the transaction engine 205 of FIG. 3, thecryptographic engine 220 comprises an operating system 605 having atleast a listening and a handling thread of a modified version of aconventional Web server, such as, for example, Web servers availablefrom Apache. As shown in FIG. 8, the cryptographic engine 220 comprisesa data splitting module 610 and a data assembling module 620 thatfunction similar to those of FIG. 5. However, according to oneembodiment, the data splitting module 610 and the data assembling module620 process cryptographic key data, as opposed to the foregoingenrollment authentication data. Although, a skilled artisan willrecognize from the disclosure herein that the data splitting module 910and the data splitting module 620 may be combined with those of theauthentication engine 215.

The cryptographic engine 220 also comprises a cryptographic handlingmodule 625 configured to perform some or all of a wide number ofcryptographic functions. According to one embodiment, the cryptographichandling module 625 may comprise software modules or programs, hardware,or both. According to another embodiment, the cryptographic handlingmodule 625 may perform data comparisons, data hashing, data encryptionor decryption, digital signature verification or creation, digitalcertificate generation, storage, or requests, cryptographic keygeneration, or the like. Moreover, a skilled artisan will recognize fromthe disclosure herein that the cryptographic handling module 625 mayadvantageously comprises a public-key infrastructure, such as PrettyGood Privacy (PGP), an RSA-based public-key system, or a wide number ofalternative key management systems. In addition, the cryptographichandling module 625 may perform public-key encryption, symmetric-keyencryption, or both. In addition to the foregoing, the cryptographichandling module 625 may include one or more computer programs ormodules, hardware, or both, for implementing seamless, transparent,interoperability functions.

A skilled artisan will also recognize from the disclosure herein thatthe cryptographic functionality may include a wide number of functionsgenerally surrounding cryptographic key management systems.

FIG. 7 illustrates a simplified block diagram of a depository system 700according to aspects of an embodiment of the invention. As shown in FIG.7, the depository system 700 advantageously comprises multiple datastorage facilities, for example, data storage facilities D1, D2, D3, andD4. According to one embodiment of the invention, each of the datastorage facilities D1 through D4 may advantageously comprise some or allof the elements disclosed with reference to the depository 210 of FIG.4. Similar to the depository 210, the data storage facilities D1 throughD4 communicate with the transaction engine 205, the authenticationengine 215, and the cryptographic engine 220, preferably throughconventional SSL communication links transferring, for example, XMLdocuments. Communications from the transaction engine 205 mayadvantageously include requests for data, wherein the request isadvantageously broadcast to the IP address of each data storage facilityD1 through D4. On the other hand, the transaction engine 205 maybroadcast requests to particular data storage facilities based on a widenumber of criteria, such as, for example, response time, server loads,maintenance schedules, or the like.

In response to requests for data from the transaction engine 205, thedepository system 700 advantageously forwards stored data to theauthentication engine 215 and the cryptographic engine 220. Therespective data assembling modules receive the forwarded data andassemble the data into useable formats. On the other hand,communications from the authentication engine 215 and the cryptographicengine 220 to the data storage facilities D1 through D4 may include thetransmission of sensitive data to be stored. For example, according toone embodiment, the authentication engine 215 and the cryptographicengine 220 may advantageously employ their respective data splittingmodules to divide sensitive data into undecipherable portions, and thentransmit one or more undecipherable portions of the sensitive data to aparticular data storage facility.

According to one embodiment, each data storage facility, D1 through D4,comprises a separate and independent storage system, such as, forexample, a directory server. According to another embodiment of theinvention, the depository system 700 comprises multiple geographicallyseparated independent data storage systems. By distributing thesensitive data into distinct and independent storage facilities D1through D4, some or all of which may be advantageously geographicallyseparated, the depository system 700 provides redundancy along withadditional security measures. For example, according to one embodiment,only data from two of the multiple data storage facilities, D1 throughD4, are needed to decipher and reassemble the sensitive data. Thus, asmany as two of the four data storage facilities D1 through D4 may beinoperative due to maintenance, system failure, power failure, or thelike, without affecting the functionality of the trust engine 110. Inaddition, because, according to one embodiment, the data stored in eachdata storage facility is randomized and undecipherable, compromise ofany individual data storage facility does not necessarily compromise thesensitive data. Moreover, in the embodiment having geographicallyseparation of the data storage facilities, a compromise of multiplegeographically remote facilities becomes increasingly difficult. Infact, even a rouge employee will be greatly challenged to subvert theneeded multiple independent geographically remote data storagefacilities.

Although the depository system 700 is disclosed with reference to itspreferred and alternative embodiments, the invention is not intended tobe limited thereby. Rather, a skilled artisan will recognize from thedisclosure herein, a wide number of alternatives for the depositorysystem 700. For example, the depository system 700 may comprise two ormore data storage facilities. In addition, sensitive data may bemathematically operated 25 such that portions from two or more datastorage facilities are needed to reassemble and decipher the sensitivedata.

As mentioned in the foregoing, the authentication engine 215 and thecryptographic engine 220 each include a data splitting module 520 and610, respectively, for splitting sensitive data, such as, for example,the authentication data and the cryptographic key data. FIG. 8illustrates a flowchart of a data splitting process 800 performed by thedata splitting module according to aspects of an embodiment of theinvention. As shown in FIG. 8, the data splitting process 800 begins atstep 805 when sensitive data “S” is received by the data splittingmodule of the authentication engine 215 or the cryptographic engine 220.Preferably, in step 810, the data splitting module then generates asubstantially random number, value, or string or set of bits, “A.” Forexample, the random number A may be generated in a wide number ofvarying conventional techniques available to one of ordinary skill inthe art, for producing high quality random numbers suitable for use incryptographic applications. In addition, according to one embodiment,the random number A comprises a bit length equal to the bit length ofthe sensitive data, S.

In addition, in step 820 the data splitting process 800 generatesanother statistically random number “C.” According to the preferredembodiment, the generation of the statistically random numbers A and Cmay advantageously be done in parallel. The data splitting module thencombines the numbers A and C with the sensitive data S such that newnumbers “B” and “D” are generated. For example, number B may comprisethe binary combination of A XOR S and number D may comprise the binarycombination of C XOR S. The foregoing combinations preferably occur insteps 825 and 830, respectively, and, according to one embodiment, theforegoing combinations also occur in parallel. The data splittingprocess 800 then proceeds to step 835 where the random numbers A and Cand the numbers B and D are paired such that none of the pairingscontain sufficient data, by themselves, to reorganize and decipher theoriginal sensitive data S. For example, the numbers may be paired asfollows: AC, AD, BC, and BD. According to one embodiment, each of theforegoing pairings is distributed to one of the depositories D1 throughD4 of FIG. 7. According to another embodiment, each of the foregoingpairings is randomly distributed to one of the depositories D1 throughD4. For example, during a first data splitting process 800, the pairingAC may be sent to depository D2, through, for example, a randomselection of D2's IP address. Then, during a second data splittingprocess 800, the pairing AC may be sent to depository D4, through, forexample, a random selection of D4's IP address.

Based on the foregoing, the data splitting process 800 advantageouslyplaces portions of the sensitive data in each of the four data storagefacilities D1 through D4, such that no single data storage facility D1through D4 includes sufficient encrypted data to recreate the originalsensitive data S. As mentioned in the foregoing, such randomization ofthe data into individually unusable encrypted portions increasessecurity and provides for maintained trust in the data even if one ofthe data storage facilities, D! through D4, is compromised.

Although the data splitting process 800 is disclosed with reference toits preferred embodiment, the invention is not intended to be limitedthereby. Rather a skilled artisan will recognize from the disclosureherein, a wide number of alternatives for the data splitting process800. For example, the data splitting process may advantageously Splitthe data into two numbers, for example, random number A and number Band, randomly distribute A and B through two data storage facilities.Moreover, the data splitting process 800 may advantageously split thedata among a wide number of data storage facilities through generationof an additional random numbers.

As mentioned in the foregoing, in order to recreate the sensitive dataS, the data portions need to be derandomized and reorganized. Thisprocess may advantageously occur in the data assembling modules, 525 and620, of the authentication engine 215 and the cryptographic engine 220,respectively. The data assembling module, for example, data assemblymodule 525, receives data portions from the data storage facilities D1through D4, and reassembles the data into useable form. For example,according to one embodiment where the data splitting module 520 employedthe data splitting process 800 of FIG. 8, the data assembling module 525uses data portions from at least two of the data storage facilities D1through D4 to recreate the sensitive data S. For example, the pairingsof AC, AD, BC, and BD, were distributed such that any two provide one ofA and B, or, C and D. Noting that S=A XOR B or S=C XOR D indicates thatwhen the data assembling module receives one of A and B, or, C and D,the data assembling module 525 can advantageously reassemble thesensitive data S. Thus, the data assembling module 525 may assemble thesensitive data S, when, for example, it receives data portions from atleast the first two of the data storage facilities D! through D4 torespond to an assemble request by the trust engine 110.

Based on the above data splitting and assembling processes, thesensitive data S exists in usable format only in a limited area of thetrust engine 110. For example, when the sensitive data S includesenrollment authentication data, usable, nonrandomized enrollmentauthentication data is available only in the authentication engine 215Likewise, when the sensitive data S includes private cryptographic keydata, usable, nonrandomized private cryptographic key data is availableonly in the cryptographic engine 220.

Although the data splitting and assembling processes are disclosed withreference to their preferred embodiments, the invention is not intendedto be limited thereby. Rather, a skilled artisan will recognize from thedisclosure herein, a wide number of alternatives for splitting andreassembling the sensitive data S. For example, public-key encryptionmay be used to further secure the data at the data storage facilities D1through D4.

FIG. 9A illustrates a data flow of an enrollment process 900 accordingto aspects of an embodiment of the invention. As shown in FIG. 9A, theenrollment process 900 begins at step 905 when a user desires to enrollwith the trust engine 110 of the cryptographic system 100. According tothis embodiment, the user system 105 advantageously includes aclient-side applet, such as a Java-based, that queries the user to enterenrollment data, such as demographic data and enrollment authenticationdata. According to one embodiment, the enrollment authentication dataincludes user ID, password(s), biometric(s), or the like. According toone embodiment, during the querying process, the client-side appletpreferably communicates with the trust engine 110 to ensure that achosen user ID is unique. When the user ID is nonunique, the trustengine 110 may advantageously suggest a unique user ID. The client-sideapplet gathers the enrollment data and transmits the enrollment data,for example, through and XML document, to the trust engine 110, and inparticular, to the transaction engine 205. According to one embodiment,the transmission is encoded with the public key of the authenticationengine 215.

According to one embodiment, the user performs a single enrollmentduring step 905 of the enrollment process 900. For example, the userenrolls himself or herself as a particular person, such as Joe User.When Joe User desires to enroll as Joe User, CEO of Mega Corp., thenaccording to this embodiment, Joe User enrolls a second time, receives asecond unique user ID and the trust engine 110 does not associate thetwo identities. According to another embodiment of the invention, theenrollment process 900 provides for multiple user identities for asingle user ED. Thus, in the above example, the trust engine 110 willadvantageously associate the two identities of Joe User. As will beunderstood by a skilled artisan from the disclosure herein, a user mayhave many identities, for example, Joe User the head of household, JoeUser the member of the Charitable Foundations, and the like. Even thoughthe user may have multiple identities, according to this embodiment, thetrust engine 110 preferably stores only one set of enrollment data.Moreover, users may advantageously add, edit/update, or deleteidentities as they are needed.

Although the enrollment process 900 is disclosed with reference to itspreferred embodiment, the invention is not intended to be limitedthereby. Rather, a skilled artisan will recognize from the disclosureherein, a wide number of alternatives for gathering of enrollment data,and in particular, enrollment authentication data. For example, theapplet may be common object model (COM)based applet or the like.

On the other hand, the enrollment process may include graded enrollment.For example, at a lowest level of enrollment, the user may enroll overthe communication link 125 without producing documentation as to his orher identity. According to an increased level of enrollment, the userenrolls using a trusted third party, such as a digital notary. Forexample, and the user may appear in person to the trusted third party,produce credentials such as a birth certificate, driver's license,military ID, or the like, and the trusted third party may advantageouslyinclude, for example, their digital signature in enrollment submission.The trusted third party may include an actual notary, a governmentagency, such as the Post Office or Department of Motor Vehicles, a humanresources person in a large company enrolling an employee, or the like.A skilled artisan will understand from the disclosure herein that a widenumber of varying levels of enrollment may occur during the enrollmentprocess 900.

After receiving the enrollment authentication data, at step 915, thetransaction engine 205, using conventional FULL SSL technology forwardsthe enrollment authentication data to the authentication engine 215. Instep 920, the authentication engine 215 decrypts the enrollmentauthentication data using the private key of the authentication engine215. In addition, the authentication engine 215 employs the datasplitting module to mathematically operate on the enrollmentauthentication data so as to split the data into at least twoindependently undecipherable, randomized, numbers. As mentioned in theforegoing, the at least two numbers may comprise a statistically randomnumber and a binary XOR′ed number. In step 925, the authenticationengine 215 forwards each portion of the randomized numbers to one of thedata storage facilities D1 through D4. As mentioned in the foregoing,the authentication engine 215 may also advantageously randomize whichportions are transferred to which depositories.

Often during the enrollment process 900, the user will also desire tohave a digital certificate issued such that he or she may receiveencrypted documents from others outside the cryptographic system 100. Asmentioned in the foregoing, the certificate authority 115 generallyissues digital certificates according to one or more of severalconventional standards. Generally, the digital certificate includes apublic key of the user or system, which is known to everyone.

Whether the user requests a digital certificate at enrollment, or atanother time, the request is transferred through the trust engine 110 tothe authentication engine 215. According to one embodiment, the requestincludes an XML document having, for example, the proper name of theuser. According to step 935, the authentication engine 215 transfers therequest to the cryptographic engine 220 instructing the cryptographicengine 220 to generate a cryptographic key or key pair.

Upon request, at step 935, the cryptographic engine 220 generates atleast one cryptographic key. According to one embodiment, thecryptographic handling module 625 generates a key pair, where one key isused as a private key, and one is used as a public key. Thecryptographic engine 220 stores the private key and, according to oneembodiment, a copy of the public key. In step 945, the cryptographicengine 220 transmits a request for a digital certificate to thetransaction engine 205. According to one embodiment, the requestadvantageously includes a standardized request, such as PKCS 10,embedded in, for example, and XML document. The request for a digitalcertificate may advantageously correspond to one or more certificateauthorities and the one or more standard formats the certificateauthorities require.

In step 950 the transaction engine 205 forwards this request to thecertificate authority 115, who, in step 955, returns a digitalcertificate. The return digital certificate may advantageously be in astandardized format, such as PKCS7, or in a proprietary format of one ormore of the certificate authorities 115. In step 960, the digitalcertificate is received by the transaction engine 205, and a copy isforwarded to the user and a copy is stored with the trust engine 110.The trust engine 110 stores a copy of the certificate such that thetrust engine 110 will not need to rely on the availability of thecertificate authority 115. For example, when the user desires to send adigital certificate, or a third party requests the user's digitalcertificate, the request for the digital certificate is typically sentto the certificate authority 115. However, if the certificate authority115 is conducting maintenance or has been victim of a failure orsecurity compromise, the digital certificate may not be available.

At any time after issuing the cryptographic keys, the cryptographicengine 220 may advantageously employ the data splitting process 800described above such that the cryptographic keys are split intoindependently undecipherable randomized numbers. Similar to theauthentication data, at step 965 the cryptographic engine 220 transfersthe randomized numbers to the data storage facilities D1 through D4.

A skilled artisan will recognize from the disclosure herein that theuser may request a digital certificate anytime after enrollment.Moreover, the communications between systems may advantageously includeFULL SSL or public-key encryption technologies. Moreover, the enrollmentprocess may issue multiple digital certificates from multiplecertificate authorities, including one or more proprietary certificateauthorities internal or external to the trust engine 110.

As disclosed in steps 935 through 960, one embodiment of the inventionincludes the request for a certificate that is eventually stored on thetrust engine 110. Because, according to one embodiment, thecryptographic handling module 625 issues the keys used by the trustengine 110, each certificate corresponds to a private key. Therefore,the trust engine 110 may advantageously provide for interoperabilitythrough monitoring the certificates owned by, or associated with, auser. For example, when the cryptographic engine 220 receives a requestfor a cryptographic function, the cryptographic handling module 625 mayinvestigate the certificates owned by the requesting user to determinewhether the user owns a private key matching the attributes of therequest. When such a certificate exists, the cryptographic handlingmodule 625 may use the certificate or the public or private keysassociated therewith, to perform the requested function. When such acertificate does not exist, the cryptographic handling module 625 mayadvantageously and transparently perform a number of actions to attemptto remedy the lack of an appropriate key. For example, FIG. 9Billustrates a flowchart of an interoperability process 970, whichaccording to aspects of an embodiment of the invention, discloses theforegoing steps to ensure the cryptographic handling module 625 performscryptographic functions using appropriate keys.

As shown in FIG. 9B, the interoperability process 970 begins with step972 where the cryptographic handling module 925 determines the type ofcertificate desired. According to one embodiment of the invention, thetype of certificate may advantageously be specified in the request forcryptographic functions, or other data provided by the requestor.According to another embodiment, the certificate type may be ascertainedby the data format of the request. For example, the cryptographichandling module 925 may advantageously recognize the request correspondsto a particular type.

According to one embodiment, the certificate type may include one ormore algorithm standards, for example, RSA, ELGAMAL, or the like. Inaddition, the certificate type may include one or more key types, suchas symmetric keys, public keys, strong encryption keys such as 256 bitkeys, less secure keys, or the like. Moreover, the certificate type mayinclude upgrades or replacements of one or more of the foregoingalgorithm standards or keys, one or more message or data formats, one ormore data encapsulation or encoding schemes, such as Base 32 or Base 64.The certificate type may also include compatibility with one or morethird-party cryptographic applications or interfaces, one or morecommunication protocols, or one or more certificate standards orprotocols. A skilled artisan will recognize from the disclosure hereinthat other differences may exist in certificate types, and translationsto and from those differences may be implemented as disclosed herein.

Once the cryptographic handling module 625 determines the certificatetype, the interoperability process 970 proceeds to step 974, anddetermines whether the user owns a certificate matching the typedetermined in step 974. When the user owns a matching certificate, forexample, the trust engine 110 has access to the matching certificatethrough, for example, prior storage thereof, the cryptographic handlingmodule 625 knows that a matching private key is also stored within thetrust engine 110. For example, the matching private key may be storedwithin the depository 210 or depository system 700. The cryptographichandling module 625 may advantageously request the matching private keybe assembled from, for example, the depository 210, and then in step976, use the matching private key to perform cryptographic actions orfunctions. For example, as mentioned in the foregoing, the cryptographichandling module 625 may advantageously perform hashing, hashcomparisons, data encryption or decryption, digital signatureverification or creation, or the like.

When the user does not own a matching certificate, the interoperabilityprocess 970 proceeds to step 978 where the cryptographic handling module625 determines whether the users owns a cross-certified certificate.According to one embodiment, cross-certification between certificateauthorities occurs when a first certificate authority determines totrust certificates from a second certificate authority. In other words,the first certificate authority determines that certificates from thesecond certificate authority meets certain quality standards, andtherefore, may be “certified” as equivalent to the first certificateauthority's own certificates. Cross-certification becomes more complexwhen the certificate authorities issue, for example, certificates havinglevels of trust. For example, the first certificate authority mayprovide three levels of trust for a particular certificate, usuallybased on the degree of reliability in the enrollment process, while thesecond certificate authority may provide seven levels of trust.Cross-certification may advantageously track which levels and which thecertificates from the second certificate authority may be substitutedfor which levels and which certificates from the first. When theforegoing cross-certification is done officially and publicly betweentwo certification authorities, the mapping of certificates and levels toone another is often called “chaining.”

According to another embodiment of the invention, the cryptographichandling module 625 may advantageously develop cross-certificationsoutside those agreed upon by the certificate authorities. For example,the cryptographic handling module 625 may access a first certificateauthority's certificate practice statement (CPS), or other publishedpolicy statement, and using, for example, the authentication tokensrequired by particular trust levels, match the first certificateauthority's certificates to those of another certificate authority.

When, in step 978, the cryptographic handling module 625 determines thatthe users owns a cross-certified certificate, the interoperabilityprocess 970 proceeds to step 976, and performs the cryptographic actionor function using the cross-certified public key, private key, or both.Alternatively, when the cryptographic handling module 625 determinesthat the users does not own a cross-certified certificate, theinteroperability process 970 proceeds to step 980, where thecryptographic handling module 625 selects a certificate authority thatissues the requested certificate type, or a certificate cross-certifiedthereto. In step 982, the cryptographic handling module 625 determineswhether the user enrollment authentication data, discussed in theforegoing, meets the authentication requirements of the chosencertificate authority. For example, if the user enrolled over a networkby, for example, answering demographic and other questions, theauthentication data provided may establish a lower level of trust than auser providing biometric data and appearing before a third-party, suchas, for example, a notary. According to one embodiment, the foregoingauthentication requirements may advantageously be provided in the chosenauthentication authority's CPS.

When the user has provided the trust engine 110 with enrollmentauthentication data meeting the requirements of chosen certificateauthority, the interoperability process 970 proceeds to step 984, wherethe cryptographic handling module 625 acquires the certificate from thechosen certificate authority. According to one embodiment, thecryptographic handling module 625 acquires the certificate by followingsteps 945 through 960 of the enrollment process 900. For example, thecryptographic handling module 625 may advantageously employ one or morepublic keys from one or more of the key pairs already available to thecryptographic engine 220, to request the certificate from thecertificate authority. According to another embodiment, thecryptographic handling module 625 may advantageously generate one ormore new key pairs, and use the public keys corresponding thereto, torequest the certificate from the certificate authority.

According to another embodiment, the trust engine 110 may advantageouslyinclude one or more certificate issuing modules capable of issuing oneor more certificate types. According to this embodiment, the certificateissuing module may provide the foregoing certificate. When thecryptographic handling module 625 acquires the certificate, theinteroperability process 970 proceeds to step 976, and performs thecryptographic action or function using the public key, private key, orboth corresponding to the acquired certificate.

When the user, in step 982, has not provided the trust engine 110 withenrollment authentication data 35 meeting the requirements of chosencertificate authority, the cryptographic handling module 625 determines,in step 986 whether there are other certificate authorities that havedifferent authentication requirements. For example, the cryptographichandling module 625 may look for certificate authorities having lowerauthentication requirements, but still issue the chosen certificates, orcross-certifications thereof.

When the foregoing certificate authority having lower requirementsexists, the interoperability process 970 proceeds to step 980 andchooses that certificate authority. Alternatively, when no suchcertificate authority exists, in step 988, the trust engine 110 mayrequest additional authentication tokens from the user. For example, thetrust engine 110 may request new enrollment authentication datacomprising, for example, biometric data. Also, the trust engine 110 mayrequest the user appear before a trusted third party and provideappropriate authenticating credentials, such as, for example, appearingbefore a notary with a drivers license, social security card, bank card,birth certificate, military ID, or the like. When the trust engine 110receives updated authentication data, the interoperability process 970proceeds to Step 984 and acquires the foregoing chosen certificate.

Through the foregoing interoperability process 970, the cryptographichandling module 625 advantageously provides seamless, transparent,translations and conversions between differing cryptographic systems. Askilled artisan will recognize from the disclosure herein, a wide numberof advantages and implementations of the foregoing interoperable system.For example, the foregoing step 986 of the interoperability process 970may advantageously include aspects of trust arbitrage, discussed infurther detail below, where the certificate authority may under specialcircumstances accept lower levels of cross-certification. In addition,the interoperability process 970 may include ensuring interoperabilitybetween and employment of standard certificate revocations, such asemploying certificate revocation lists (CRL), online certificate statusprotocols (OCSP), or the like.

FIG. 10 illustrates a data flow of an authentication process 1000according to aspects of an embodiment of the invention. According to oneembodiment, the authentication process 1000 includes gathering currentauthentication data from a user and comparing that to the enrollmentauthentication data of the user. For example, the authentication process1000 begins at step 1005 where a user desires to perform a transactionwith, for example, a vendor. Such transactions may include, for example,selecting a purchase option, requesting access to a restricted area ordevice of the vendor system 120, or the like. At step 1010, a vendorprovides the user with a transaction ID and an authentication request.The transaction ID may advantageously include a 192 bit quantity havinga 32 bit timestamp concatenated with a 128 bit random quantity, or a“nonce,” concatenated with a 32 bit vendor specific constant. Such atransaction ID uniquely identifies the transaction such that copycattransactions can be refused by the trust engine 110.

The authentication request may advantageously include what level ofauthentication is needed for a particular transaction. For example, thevendor may specify a particular level of confidence that is required forthe transaction at issue, if authentication cannot be made to this levelof confidence, as will be discussed below, the transaction will notoccur without either further authentication by the user to raise thelevel of confidence, or a change in the terms of the authenticationbetween the vendor and the server. These issues are discussed morecompletely below.

According to one embodiment, the transaction ID and the authenticationrequest may advantageously generated by a vendor-side applet or othersoftware program. In addition, the transmission of the transaction IDand authentication data may include one or more XML documents encryptedusing conventional SSL technology, such as, for example, ½ SSL, or, inother words vendor-side authenticated SSL.

After the user system 105 receives the transaction ID and authenticationrequest, the user system 105 gathers the current authentication data,potentially including current biometric information, from the user. Theuser system 105, at step 1015, encrypts at least the currentauthentication data—B′″ and the transaction ID, with the public key ofthe authentication engine 215, and transfers that data to the trustengine 110. The transmission preferably comprises XML documentsencrypted with at least conventional ‘A SSL technology. In step 1020,the transaction engine 205 receives the transmission, preferablyrecognizes the data format or request in the URL or URI, and forwardsthe transmission to the authentication engine 215.

During steps 1015 and 1020, the vendor system 120, at step 1025,forwards the transaction ID and the authentication request to the trustengine 110, using the preferred FULL SSL technology. This communicationmay also include a vendor ID, although vendor identification may also becommunicated through a non-random portion of the transaction ID. Atsteps 1030 and 1035, the transaction engine 205 receives thecommunication, creates a record in the audit trail, and generates arequest for the user's enrollment authentication data to be assembledfrom the data storage facilities D1 through D4. At step 1040, thedepository system 700 transfers the portions of the enrollmentauthentication data corresponding to the user to the authenticationengine 215. At step 1045, the authentication engine 215 decrypts thetransmission using its private key and compares the enrollmentauthentication data to the current authentication data provided by theuser.

The comparison of step 1045 may advantageously apply heuristical contextsensitive authentication, as referred to in the forgoing, and discussedin further detail below. For example, if the biometric informationreceived does not match perfectly, a lower confidence match results. Inparticular embodiments, the level of confidence of the authentication isbalanced against the nature of the transaction and the desires of boththe user and the vendor. Again, this is discussed in greater detailbelow.

At step 1050, the authentication engine 215 fills in the authenticationrequest with the result of the comparison of step 1045. According to oneembodiment of the invention, the authentication request is filled with aYES/NO or TRUE/FALSE result of the authentication process 1000. In step1055 the filled-in authentication request is returned to the vendor forthe vendor to act upon, for example, allowing the user to complete thetransaction that initiated the authentication request. According to oneembodiment, a confirmation message is passed to the user.

Based on the foregoing, the authentication process 1000 advantageouslykeeps sensitive data secure and produces results configured to maintainthe integrity of the sensitive data. For example, the sensitive data isassembled only inside the authentication engine 215. For example, theenrollment authentication data is undecipherable until it is assembledin the authentication engine 215 by the data assembling module, and thecurrent authentication data is undecipherable until it is unwrapped bythe conventional SSL technology and the private key of theauthentication engine 215. Moreover, the authentication resulttransmitted to the vendor does not include the sensitive data, and theuser may not even know whether he or she produced valid authenticationdata.

Although the authentication process 1000 is disclosed with reference toits preferred and alternative embodiments, the invention is not intendedto be limited thereby. Rather, a skilled artisan will recognize from thedisclosure herein, a wide number of alternatives for the authenticationprocess 1000. For example, the vendor may advantageously be replaced byalmost any requesting application, even those residing with the usersystem 105. For example, a client application, such as Microsoft Word,may use an application program interface (API) or a cryptographic API(CAPI) to request authentication before unlocking a document.Alternatively, a mail server, a network, a cellular phone, a personal ormobile computing device, a workstation, or the like, may all makeauthentication requests that can be filled by the authentication process1000. In fact, after providing the foregoing trusted authenticationprocess 1000, the requesting application or device may provide access toor use of a wide number of electronic or computer devices or systems.

Moreover, the authentication process 1000 may employ a wide number ofalternative procedures in the event of authentication failure. Forexample, authentication failure may maintain the same transaction ID andrequest that the user reenter his or her current authentication data. Asmentioned in the foregoing, use of the same transaction ID allows thecomparator of the authentication engine 215 to monitor and limit thenumber of authentication attempts for a particular transaction, therebycreating a more secure cryptographic system 100. In addition, theauthentication process 1000 may be advantageously be employed to developelegant single sign-on solutions, such as, unlocking a sensitive datavault. For example, successful or positive authentication may providethe authenticated user the ability to automatically access any number ofpasswords for an almost limitless number of systems and applications.For example, authentication of a user may provide the user access topassword, login, financial credentials, or the like, associated withmultiple online vendors, a local area network, various personalcomputing devices, Internet service providers, auction providers,investment brokerages, or the like. By employing a sensitive data vault,users may choose truly large and random passwords because they no longerneed to remember them through association. Rather, the authenticationprocess 1000 provides access thereto. For example, a user may choose arandom alphanumeric string that is twenty plus digits in length ratherthan something associated with a memorable data, name, etc.

According to one embodiment, a sensitive data vault associated with agiven user may advantageously be stored in the data storage facilitiesof the depository 210, or split and stored in the depository system 700.According to this embodiment, after positive user authentication, thetrust engine 110 serves the requested sensitive data, such as, forexample, to the appropriate password to the requesting application.According to another embodiment, the trust engine 110 may include aseparate system for storing the sensitive data vault. For example, thetrust engine 110 may include a stand-alone software engine implementingthe data vault functionality and figuratively residing “behind” theforegoing front-end security system of the trust engine 110. Accordingto this embodiment, the software engine serves the requested sensitivedata after the software engine receives a signal indicating positiveuser authentication from the trust engine 110.

In yet another embodiment, the data vault may be implemented by athirdparty system. Similar to the software engine embodiment, thethird-party system may advantageously serve the requested sensitive dataafter the third-party system receives a signal indicating positive userauthentication from the trust engine 110. According to yet anotherembodiment, the data vault may be implemented on the user system 105. Auser-side software engine may advantageously serve the foregoing dataafter receiving a signal indicating positive user authentication fromthe trust engine 110.

Although the foregoing data vaults are disclosed with reference toalternative embodiments, a skilled artisan will recognize from thedisclosure herein, a wide number of additional implementations thereof.For example, a particular data vault may include aspects from some orall of the foregoing embodiments. In addition, any of the foregoing datavaults may employ one or more authentication requests at varying times.For example, any of the data vaults may require authentication every oneor more transactions, periodically, every one or more sessions, everyaccess to one or more Webpages or Websites, at one or more otherspecified intervals, or the like.

FIG. 11 illustrates a data flow of a signing process 1100 according toaspects of an embodiment of the invention. As shown in FIG. 11, thesigning process 1100 includes steps similar to those of theauthentication process 1000 described in the foregoing with reference toFIG. 10. According to one embodiment of the invention, the signingprocess 1100 first authenticates the user and then performs one or moreof several digital signing functions as will be discussed in furtherdetail below. According to another embodiment, the signing process 1100may advantageously store data related thereto, such as hashes ofmessages or documents, or the like. This data may advantageously be usedin an audit or any other event, such as for example, when aparticipating party attempts to repudiate a transaction.

As shown in FIG. 11, during the authentication steps, the user andvendor may advantageously agree on a message, such as, for example, acontract. During signing, the signing process 1100 advantageouslyensures that the contract signed by the user is identical to thecontract supplied by the vendor. Therefore, according to one embodiment,during authentication, the vendor and the user include a hash of theirrespective copies of the message or contract, in the data transmitted tothe authentication engine 215. By employing only a hash of a message orcontract, the trust engine 110 may advantageously store a significantlyreduced amount of data, providing for a more efficient and costeffective cryptographic system. In addition, the stored hash may beadvantageously compared to a hash of a document in question to determinewhether the document in question matches one signed by any of theparties. The ability to determine whether the document is identical toone relating to a transaction provides for additional evidence that canbe used against a claim for repudiation by a party to a transaction.

In step 1103, the authentication engine 215 assembles the enrollmentauthentication data and compares it to the current authentication dataprovided by the user. When the comparator of the authentication engine215 indicates that the enrollment authentication data matches thecurrent authentication data, the comparator of the authentication engine215 also compares the hash of the message supplied by the vendor to thehash of the message supplied by the user. Thus, the authenticationengine 215 advantageously ensures that the message agreed to by the useris identical to that agreed to by the vendor.

In step 1105, the authentication engine 215 transmits a digitalsignature request to the cryptographic engine 220. According to oneembodiment of the invention, the request includes a hash of the messageor contract. However, a skill artisan will recognize from the disclosureherein that the cryptographic engine 220 may encrypt virtually any textto form the desired digital signature. Returning to step 1105, thedigital signature request preferably comprises an XML documentcommunicated through conventional SSL technologies.

In step 1110, the authentication engine 215 transmits a request to eachof the data storage facilities D1 through D4, such that each of the datastorage facilities D1 through D4 transmit their respective portion ofthe cryptographic key or keys corresponding to a signing party.According to another embodiment, the cryptographic engine 220 employssome or all of the steps of the interoperability process 970 discussedin the foregoing, such that the cryptographic engine 220 firstdetermines the appropriate key or keys to request from the depository210 or the depository system 700 for the signing party, and takesactions to provide appropriate matching keys. According to still anotherembodiment, the authentication engine 215 or the cryptographic engine220 may advantageously request one or more of the keys associated withthe signing party and stored in the depository 210 or depository system700.

According to one embodiment, the signing party includes one or both theuser and the vendor. In such case, the authentication engine 215advantageously requests the cryptographic keys corresponding to the userand/or the vendor. According to another embodiment, the signing partyincludes the trust engine 110. In this embodiment, the trust engine 110is certifying that the authentication process 1000 properlyauthenticated the user, vendor, or both. Therefore, the authenticationengine 215 requests the cryptographic key of the trust engine 110, suchas, for example, the key belonging to the cryptographic engine 220, toperform the digital signature. According to another embodiment, thetrust engine 110 performs a digital notary-like function. In thisembodiment, the signing party includes the user, vendor, or both, alongwith the trust engine 110. Thus, the trust engine 110 provides thedigital signature of the user and/or vendor, and then indicates with itsown digital signature that the user and/or vendor were properlyauthenticated. In this embodiment, the authentication engine 215 mayadvantageously request assembly of the cryptographic keys correspondingto the user, the vendor, or both. According to another embodiment, theauthentication engine 215 may advantageously request assembly of thecryptographic keys corresponding to the trust engine 110.

According to another embodiment, the trust engine 110 performs power ofattorney-like functions. For example, the trust engine 110 may digitallysign the message on behalf of a third party. In such case, theauthentication engine 215 requests the cryptographic keys associatedwith the third party. According to this embodiment, the signing process1100 may advantageously include authentication of the third party,before allowing power of attorney-like functions. In addition, theauthentication process 1000 may include a check for third partyconstraints, such as, for example, business logic or the like dictatingwhen and in what circumstances a particular third-party's signature maybe used.

Based on the foregoing, in step 1110, the authentication enginerequested the cryptographic keys from the data storage facilities D1through D4 corresponding to the signing party. In step 1115, the datastorage facilities D1 through D4 transmit their respective portions ofthe cryptographic key corresponding to the signing party to thecryptographic engine 220. According to one embodiment, the foregoingtransmissions include SSL technologies. According to another embodiment,the foregoing transmissions may advantageously be super-encrypted withthe public key of the cryptographic engine 220.

In step 1120, the cryptographic engine 220 assembles the foregoingcryptographic keys of the signing party and encrypts the messagetherewith, thereby fanning the digital signature(s). In step 1125 of thesigning process 1100, the cryptographic engine 220 transmits the digitalsignature(s) to the authentication engine 215. In step 1130, theauthentication engine 215 transmits the filled-in authentication requestalong with a copy of the hashed message and the digital signature(s) tothe transaction engine 205. In step 1135, the transaction engine 205transmits a receipt comprising the transaction ID, an indication ofwhether the authentication was successful, and the digital signature(s),to the vendor. According to one embodiment, the foregoing transmissionmay advantageously include the digital signature of the trust engine110. For example, the trust engine 110 may encrypt the hash of thereceipt with its private key, thereby forming a digital signature to beattached to the transmission to the vendor.

According to one embodiment, the transaction engine 205 also transmits aconfirmation message to the user.

Although the signing process 1100 is disclosed with reference to itspreferred and alternative embodiments, the invention is not intended tobe limited thereby. Rather, a skilled artisan will recognize from thedisclosure herein, a wide number of alternatives for the signing process1100. For example, the vendor may be replaced with a user application,such as an email application. For example, the user may wish todigitally sign a particular email with his or her digital signature. Insuch an embodiment, the transmission throughout the signing process 1100may advantageously include only one copy of a hash of the message.Moreover, a skilled artisan will recognize from the disclosure hereinthat a wide number of client applications may request digitalsignatures. For example, the client applications may comprise wordprocessors, spreadsheets, emails, voicemail, access to restricted systemareas, or the like.

In addition, a skilled artisan will recognize from the disclosure hereinthat steps 1105 through 1120 of the signing process 1100 mayadvantageously employ some or all of the steps of the interoperabilityprocess 970 of FIG. 9B, thereby providing interoperability betweendiffering cryptographic systems that may, for example, need to processthe digital signature under differing signature types.

FIG. 12 illustrates a data flow of an encryption/decryption process 1200according to aspects of an embodiment of the invention. As shown in FIG.12, the decryption process 1200 begins by authenticating the user usingthe authentication process 1000. According to one embodiment, theauthentication process 1000 includes in the 35 authentication request, asynchronous session key. For example, in conventional PKI technologies,it is understood by skilled artisans that encrypting or decrypting datausing public and private keys is mathematically intensive and mayrequire significant system resources. However, in symmetric keycryptographic systems, or systems where the sender and receiver of amessage share a single common key that is used to encrypt and decrypt amessage, the mathematical operations are significantly simpler andfaster. Thus, in the conventional PKI technologies, the sender of amessage will generate synchronous session key, and encrypt the messageusing the simpler, faster symmetric key system. Then, the sender willencrypt the session key with the public key of the receiver. Theencrypted session key will be attached to the synchronously encryptedmessage and both data are sent to the receiver. The receiver uses his orher private key to decrypt the session key, and then uses the sessionkey to decrypt the message. Based on the foregoing, the simpler andfaster symmetric key system is used for the majority of theencryption/decryption processing. Thus, in the decryption process 1200,the decryption advantageously assumes that a synchronous key has beenencrypted with the public key of the user. Thus, as mentioned in theforegoing, the encrypted session key is included in the authenticationrequest.

Returning to the decryption process 1200, after the user has beenauthenticated in step 1205, the authentication engine 215 forwards theencrypted session key to the cryptographic engine 220. In step 1210, theauthentication engine 215 forwards a request to each of the data storagefacilities, D1 through D4, requesting the cryptographic key data of theuser. In step 1215, each data storage facility, D1 through D4, transmitstheir respective portion of the cryptographic key to the cryptographicengine 220. According to one embodiment, the foregoing transmission isencrypted with the public key of the cryptographic engine 220.

In step 1220 of the decryption process 1200, the cryptographic engine220 assembles the cryptographic key and decrypts the session keytherewith. In step 1225, the cryptographic engine forwards the sessionkey to the authentication engine 215. In step 1227, the authenticationengine 215 fills in the authentication request including the decryptedsession key, and transmits the filled-in authentication request to thetransaction engine 205. In step 1230, the transaction engine 205forwards the authentication request along with the session key to therequesting application or vendor. Then, according to one embodiment, therequesting application or vendor uses the session key to decrypt theencrypted message.

Although the decryption process 1200 is disclosed with reference to itspreferred and alternative embodiments, a skilled artisan will recognizefrom the disclosure herein, a wide number of alternatives for thedecryption process 1200. For example, the decryption process 1200 mayforego synchronous key encryption and rely on full public-keytechnology. In such an embodiment, the requesting application maytransmit the entire message to the cryptographic engine 220, or, mayemploy some type of compression or reversible hash in order to transmitthe message to the cryptographic engine 220. A skilled artisan will alsorecognize from the disclosure herein that the foregoing communicationsmay advantageously include XML documents wrapped in SSL technology.

The encryption/decryption process 1200 also provides for encryption ofdocuments or other data. Thus, in step 1235, a requesting application orvendor may advantageously transmit to the transaction engine 205 of the35 trust engine 110, a request for the public key of the user. Therequesting application or vendor makes this request because therequesting application or vendor uses the public key of the user, forexample, to encrypt the session key that will be used to encrypt thedocument or message. As mentioned in the enrollment process 900, thetransaction engine 205 stores a copy of the digital certificate of theuser, for example, in the mass storage 225. Thus, in step 1240 of theencryption process 1200, the transaction engine 205 requests the digitalcertificate of the user from the mass storage 225. In step 1245, themass storage 225 transmits the digital certificate corresponding to theuser, to the transaction engine 205. In step 1250, the transactionengine 205 transmits the digital certificate to the requestingapplication or vendor. According to one embodiment, the encryptionportion of the encryption process 1200 does not include theauthentication of a user. This is because the requesting vendor needsonly the public key of the user, and is not requesting any sensitivedata.

A skilled artisan will recognize from the disclosure herein that if aparticular user does not have a digital certificate, the trust engine110 may employ some or all of the enrollment process 900 in order togenerate a digital certificate for that particular user. Then, the trustengine 110 may initiate the encryption/decryption process 1200 andthereby provide the appropriate digital certificate. In addition, askilled artisan will recognize from the disclosure herein that steps1220 and 1235 through 1250 of the encryption/decryption process 1200 mayadvantageously employ some or all of the steps of the interoperabilityprocess of FIG. 9B, thereby providing interoperability between differingcryptographic systems that may, for example, need to process theencryption.

FIG. 13 illustrates a simplified block diagram of a trust engine system1300 according to aspects of yet another embodiment of the invention. Asshown in FIG. 13, the trust engine system 1300 comprises a plurality ofdistinct trust engines 1305, 1310, 1315, and 1320, respectively. Tofacilitate a more complete understanding of the invention, FIG. 13illustrates each trust engine, 1305, 1310, 1315, and 1320 as having atransaction engine, a depository, and an authentication engine. However,a skilled artisan will recognize that each transaction engine mayadvantageously comprise some or all of the elements and communicationchannels disclosed with reference to FIGS. 1-8. For example, oneembodiment may advantageously include trust engines having transactionengines, depositories, and cryptographic servers.

According to one embodiment of the invention, each of the trust engines1305, 1310, 1315 and 1320 are geographically separated, such that, forexample, the trust engine 1305 may reside in a first location, the trustengine 1310 may reside in a second location, the trust engine 1315 mayreside in a third location, and the trust engine 1320 may reside in afourth location. The foregoing geographic separation advantageouslydecreases system response time while increasing the security of theoverall trust engine system 1300.

For example, when a user logs onto the cryptographic system 100, theuser may be nearest the first location and may desire to beauthenticated. As described with reference to FIG. 10, to beauthenticated, the user provides current authentication data, such as abiometric or the like, and the current authentication data is comparedto that user's enrollment authentication data. Therefore, according toone example, the user advantageously provides current authenticationdata to the geographically nearest trust engine 1305. The transactionengine 1321 of the trust engine 1305 then forwards the currentauthentication data to the authentication engine 1322 also residing atthe first location. According to another embodiment, the transactionengine 1321 forwards the current authentication data to one or more ofthe authentication engines of the trust engines 1310, 1315, or 1320.

The transaction engine 1321 also requests the assembly of the enrollmentauthentication data from the depositories of, for example, each of thetrust engines, 1305 through 1320. According to this embodiment, eachdepository provides its portion of the enrollment authentication data tothe authentication engine 1322 of the trust engine 1305. Theauthentication engine 1322 then employs the encrypted data portionsfrom, for example, the first two depositories to respond, and assemblesthe enrollment authentication data into deciphered form. Theauthentication engine 1322 compares the enrollment authentication datawith the current authentication data and returns an authenticationresult to the transaction engine 1321 of the trust engine 1305.

Based on the above, the trust engine system 1300 employs the nearest oneof a plurality of geographically separated trust engines, 1305 through1320, to perform the authentication process. According to one embodimentof the invention, the routing of information to the nearest transactionengine may advantageously be performed at client-side applets executingon one or more of the user system 105, vendor system 120, or certificateauthority 115. According to an alternative embodiment, a moresophisticated decision process may be employed to select from the trustengines 1305 through 1320. For example, the decision may be based on theavailability, operability, speed of connections, load, performance,geographic proximity, or a combination thereof, of a given trust engine.

In this way, the trust engine system 1300 lowers its response time whilemaintaining the security advantages associated with geographicallyremote data storage facilities, such as those discussed with referenceto FIG. 7 where each data storage facility stores randomized portions ofsensitive data. For example, a security compromise at, for example, thedepository 1325 of the trust engine 1315 does not necessarily compromisethe sensitive data of the trust engine system 1300. This is because thedepository 1325 contains only non-decipherable randomized data that,without more, is entirely useless.

According to another embodiment, the trust engine system 1300 mayadvantageously include multiple cryptographic engines arranged similarto the authentication engines. The cryptographic engines mayadvantageously performs cryptographic functions such as those disclosedwith reference to FIGS. 1-8. According to yet another embodiment, thetrust engine system 1300 may advantageously replace the multipleauthentication engines with multiple cryptographic engines, therebyperforming cryptographic functions such as those disclosed withreference to FIGS. 1-8. According to yet another embodiment of theinvention, the trust engine system 1300 may replace each multipleauthentication engine with an engine having some or all of thefunctionality of the authentication engines, cryptographic engines, orboth, as disclosed in the foregoing.

Although the trust engine system 1300 is disclosed with reference to itspreferred and alternative embodiments, a skilled artisan will recognizethat the trust engine system 1300 may comprise portions of trust engines1305 through 1320. For example, the trust engine system 1300 may includeone or more transaction engines, one or more depositories, one or moreauthentication engines, or one or more cryptographic engines.

FIG. 14 illustrates a simplified block diagram of a trust engine system1400 according to aspects of yet another embodiment of the invention. Asshown in FIG. 14, the trust engine system 1400 includes multiple trustengines 1405, 1410, 1415 and 1420. According to one embodiment, each ofthe trust engines 1405, 1410, 1415 and 1420, comprise some or all of theelements of trust engine 110 disclosed with reference to FIGS. 1-8.According to this embodiment, when the client side applets of the usersystem 105, the vendor system 120, or the certificate authority 115,communicate with the trust engine system 1400, those communications aresent to the IP address of each of the trust engines 1405 through 1420.Further, each transaction engine of each of the trust engines, 1405,1410, 1415, and 1420, behaves similar to the transaction engine 1321 ofthe trust engine 1305 disclosed with reference to FIG. 13. For example,during an authentication process, each transaction engine of each of thetrust engines 1405, 1410, 1415, and 1420 transmits the currentauthentication data to their respective authentication engines andtransmits a request to assemble the randomized data stored in each ofthe depositories of each of the trust engines 1405 through 1420. FIG. 14does not illustrate all of these communications, as such illustrationwould become overly complex. Continuing with the authentication process,each of the depositories then communicates its portion of the randomizeddata to each of the authentication engines of the each of the trustengines 1405 through 1420. Each of the authentication engines of theeach of the trust engines employs its comparator to determine whetherthe current authentication data matches the enrollment authenticationdata provided by the depositories of each of the trust engines 1405through 1420. According to this embodiment, the result of the comparisonby each of the authentication engines is then transmitted to aredundancy module of the other three trust engines. For example, theresult of the authentication engine from the trust engine 1405 istransmitted to the redundancy modules of the trust engines 1410, 1415,and 1420. Thus, the redundancy module of the trust engine 1405 likewisereceives the result of the authentication engines from the trust engines1410, 1415, and 1420.

FIG. 15 illustrates a block diagram of the redundancy module of FIG. 14.The redundancy module comprises a comparator configured to receive theauthentication result from three authentication engines and transmitthat result to the transaction engine of the fourth trust engine. Thecomparator compares the authentication result form the threeauthentication engines, and if two of the results agree, the comparatorconcludes that the authentication result should match that of the twoagreeing authentication engines. This result is then transmitted back tothe transaction engine corresponding to the trust engine not associatedwith the three authentication engines.

Based on the foregoing, the redundancy module determines anauthentication result from data received from authentication enginesthat are preferably geographically remote from the trust engine of thatthe redundancy module. By providing such redundancy functionality, thetrust engine system 1400 ensures that a compromise of the authenticationengine of one of the trust engines 1405 through 1420, is insufficient tocompromise the authentication result of the redundancy module of thatparticular trust engine. A skilled artisan will recognize thatredundancy module functionality of the trust engine system 1400 may alsobe applied to the cryptographic engine of each of the trust engines 1405through 1420. However, such cryptographic engine communication was notshown in FIG. 14 to avoid complexity. Moreover, a skilled artisan willrecognize a wide number of alternative authentication result conflictresolution algorithms for the comparator of FIG. 15.

According to yet another embodiment of the invention, the trust enginesystem 1400 may advantageously employ the redundancy module duringcryptographic comparison steps. For example, some or all of theforegoing redundancy module disclosure with reference to FIGS. 14 and 15may advantageously be implemented during a hash comparison of documentsprovided by one or more parties during a particular transaction.

Although the foregoing invention has been described in terms of certainpreferred and alternative embodiments, other embodiments will beapparent to those of ordinary skill in the art from the disclosureherein. For example, the trust engine 110 may issue short-termcertificates, where the private cryptographic key is released to theuser for a predetermined period of time. For example, currentcertificate standards include a validity field that can be set to expireafter a predetermined amount of time. Thus, the trust engine 110 mayrelease a private key to a user where the private key would be validfor, for example, 24 hours. According to such an embodiment, the trustengine 110 may advantageously issue a new cryptographic key pair to beassociated with a particular user and then release the private key ofthe new cryptographic key pair. Then, once the private cryptographic keyis released, the trust engine 110 immediately expires any internal validuse of such private key, as it is no longer securable by the trustengine 110.

In addition, a skilled artisan will recognize that the cryptographicsystem 100 or the trust engine 110 may include the ability to recognizetypes of devices, such as a laptop, a cell phone, a network or the like.According to one embodiment, such recognition may come from datasupplied in the request for a particular service, such as, a request forauthentication leading to access or use, a request for cryptographicfunctionality, or the like. According to one embodiment, the foregoingrequest may include a unique device identifier, such as, for example, aprocessor ID. Alternatively, the request may include data in aparticular recognizable data format. For example, mobile and satellitephones often do not include the processing power for full X509.v3 heavyencryption certificates, and therefore do not request them. According tothis embodiment, the trust engine 110 may recognize the type of dataformat presented, and respond only in kind

In an additional aspect of the system described above, context sensitiveauthentication can be provided using various techniques as will bedescribed below. Context sensitive authentication, for example as shownin FIG. 16, provides the possibility of evaluating not only the actualdata which is sent by the user when attempting to authenticate himself,but also the circumstances surrounding the generation and delivery ofthat data. Such techniques may also support transaction specific trustarbitrage between the user and trust engine 110 or between the vendorand trust engine 110, as will be described below.

As discussed above, authentication is the process of proving that a useris who he says he is. Generally, authentication requires demonstratingsome fact to an authentication authority. The trust engine 110 of thepresent invention represents the authority to which a user mustauthenticate himself. The user must demonstrate to the trust engine 110that he is who he says he is by either: knowing something that only theuser should know (knowledge-based authentication), having something thatonly the user should have (token-based authentication), or by beingsomething that only the user should be (biometric-based authentication).

Examples of knowledge-based authentication include without limitation apassword, PIN number, or lock combination. Examples of token-basedauthentication include without limitation a house key, a physical creditcard, a driver's license, or a particular phone number. Examples ofbiometric-based authentication include without limitation a fingerprint,a voice analysis, or a retinal scan.

Each type of authentication has particular advantages and disadvantages,and each provides a different level of security. For example, it isgenerally harder to create a false fingerprint that matches someoneelse's than it is to overhear someone's password and repeat it. Eachtype of authentication also requires a different type of data to beknown to the authenticating authority in order to verify someone usingthat form of authentication.

As used herein, “authentication will refer broadly to the overallprocess of verifying someone's identity to be who he says he is. An“authentication technique” will refer to a particular type ofauthentication based upon a particular piece of knowledge, physicaltoken, or biometric reading. “Authentication data” refers to informationwhich is sent to or otherwise demonstrated to an authenticationauthority in order to establish identity. “Enrollment data” will referto the data which is initially submitted to an authentication authorityin order to establish a baseline for comparison with authenticationdata. An “authentication instance” will refer to the data associatedwith an attempt to authenticate by an authentication technique.

The internal protocols and communications involved in the process ofauthenticating a user is described with reference to FIG. 10 above. Thepart of this process within which the context sensitive authenticationtakes place occurs within the comparison step shown as step 1045 of FIG.10. This step takes place within the authentication engine 215 andinvolves assembling the enrollment data 410 retrieved from thedepository 210 and comparing the authentication data provided by theuser to it. One particular embodiment of this process is shown in FIG.16 and described below.

The current authentication data provided by the user and the enrollmentdata retrieved from the depository 210 are received by theauthentication engine 215 in step 1600 of FIG. 16. Both of these sets ofdata may contain data which is related to separate techniques ofauthentication. The authentication engine 215 separates theauthentication data associated with each individual authenticationinstance in step 1605. This is necessary so that the authentication datais compared with the appropriate subset of the enrollment data for theuser (e.g., fingerprint authentication data should be compared withfingerprint enrollment data, rather than password enrollment data).

Generally, authenticating a user involves one or more individualauthentication instances, depending on which authentication techniquesare available to the user. These methods are limited by the enrollmentdata which were provided by the user during his enrollment process (ifthe user did not provide a retinal scan when enrolling, he will not beable to authenticate himself using a retinal scan), as well as the meanswhich may be currently available to the user (e.g., if the user does nothave a fingerprint reader at his current location, fingerprintauthentication will not be practical). In some cases, a singleauthentication instance may be sufficient to authenticate a user;however, in certain circumstances a combination of multipleauthentication instances may be used in order to more confidentlyauthenticate a user for a particular transaction.

Each authentication instance consists of data related to a particularauthentication technique (e.g., fingerprint, password, smart card, etc.)and the circumstances which surround the capture and delivery of thedata for that particular technique. For example, a particular instanceof attempting to authenticate via password will generate not only thedata related to the password itself, but also circumstantial data, knownas “metadata”, related to that password attempt. This circumstantialdata includes information such as: the time at which the particularauthentication instance took place, the network address from which theauthentication information was delivered, as well as any otherinformation as is known to those of skill in the art which may bedetermined about the origin of the authentication data (the type ofconnection, the processor serial number, etc.).

In many cases, only a small amount of circumstantial metadata will beavailable. For example, if the user is located on a network which usesproxies or network address translation or another technique which masksthe address of the originating computer, only the address of the proxyor router may be determined. Similarly, in many cases information suchas the processor serial number will not be available because of eitherlimitations of the hardware or operating system being used, disabling ofsuch features by the operator of the system, or other limitations of theconnection between the user's system and the trust engine 110.

As shown in FIG. 16, once the individual authentication instancesrepresented within the authentication data are extracted and separatedin step 1605, the authentication engine 215 evaluates each instance forits reliability in indicating that the user is who he claims to be. Thereliability for a single authentication instance will generally bedetermined based on several factors. These may be grouped as factorsrelating to the reliability associated with the authenticationtechnique, which are evaluated in step 1610, and factors relating to thereliability of the particular authentication data provided, which areevaluated in step 1615. The first group includes without limitation theinherent reliability of the authentication technique being used, and thereliability of the enrollment data being used with that method. Thesecond group includes without limitation the degree of match between theenrollment data and the data provided with the authentication instance,and the metadata associated with that authentication instance. Each ofthese factors may vary independently of the others.

The inherent reliability of an authentication technique is based on howhard it is for an imposter to provide someone else's correct data, aswell as the overall error rates for the authentication technique. Forpasswords and knowledge based authentication methods, this reliabilityis often fairly low because there is nothing that prevents someone fromrevealing their password to another person and for that second person touse that password. Even a more complex knowledge based system may haveonly moderate reliability since knowledge may be transferred from personto person fairly easily. Token based authentication, such as having aproper smart card or using a particular terminal to perform theauthentication, is similarly of low reliability used by itself, sincethere is no guarantee that the right person is in possession of theproper token.

However, biometric techniques are more inherently reliable because it isgenerally difficult to provide someone else with the ability to use yourfingerprints in a convenient manner, even intentionally. Becausesubverting biometric authentication techniques is more difficult, theinherent reliability of biometric methods is generally higher than thatof purely knowledge or token based authentication techniques. However,even biometric techniques may have some occasions in which a falseacceptance or false rejection is generated. These occurrences may bereflected by differing reliabilities for different implementations ofthe same biometric technique. For example, a fingerprint matching systemprovided by one company may provide a higher reliability than oneprovided by a different company because one uses higher quality opticsor a better scanning resolution or some other improvement which reducesthe occurrence of false acceptances or false rejections.

Note that this reliability may be expressed in different manners. Thereliability is desirably expressed in some metric which can be used bythe heuristics 530 and algorithms of the authentication engine 215 tocalculate the confidence level of each authentication. One preferredmode of expressing these reliabilities is as a percentage or fraction.For instance, fingerprints might be assigned an inherent reliability of97%, while passwords might only be assigned an inherent reliability of50%. Those of skill in the art will recognize that these particularvalues are merely exemplary and may vary between specificimplementations.

The second factor for which reliability must be assessed is thereliability of the enrollment. This is part of the “graded enrollment”process referred to above. This reliability factor reflects thereliability of the identification provided during the initial enrollmentprocess. For instance, if the individual initially enrolls in a mannerwhere they physically produce evidence of their identity to a notary orother public official, and enrollment data is recorded at that time andnotarized, the data will be more reliable than data which is providedover a network during enrollment and only vouched for by a digitalsignature or other information which is not truly tied to theindividual.

Other enrollment techniques with varying levels of reliability includewithout limitation: enrollment at a physical office of the trust engine110 operator; enrollment at a user's place of employment; enrollment ata post office or passport office; enrollment through an affiliated ortrusted party to the trust engine 110 operator; anonymous orpseudonymous enrollment in which the enrolled identity is not yetidentified with a particular real individual, as well as such othermeans as are known in the art.

These factors reflect the trust between the trust engine 110 and thesource of identification provided during the enrollment process. Forinstance, if enrollment is performed in association with an employerduring the initial process of providing evidence of identity, thisinformation may be considered extremely reliable for purposes within thecompany, but may be trusted to a lesser degree by a government agency,or by a competitor. Therefore, trust engines operated by each of theseother organizations may assign different levels of reliability to thisenrollment.

Similarly, additional data which is submitted across a network, butwhich is authenticated by other trusted data provided during a previousenrollment with the same trust engine 110 may be considered as reliableas the original enrollment data was, even though the latter data weresubmitted across an open network. In such circumstances, a subsequentnotarization will effectively increase the level of reliabilityassociated with the original enrollment data. In this way for example,an anonymous or pseudonymous enrollment may then be raised to a fullenrollment by demonstrating to some enrollment official the identity ofthe individual matching the enrolled data.

The reliability factors discussed above are generally values which maybe determined in advance of any particular authentication instance. Thisis because they are based upon the enrollment and the technique, ratherthan the actual authentication. In one embodiment, the step ofgenerating reliability based upon these factors involves looking uppreviously determined values for this particular authenticationtechnique and the enrollment data of the user. In a further aspect of anadvantageous embodiment of the present invention, such reliabilities maybe included with the enrollment data itself. In this way, these factorsare automatically delivered to the authentication engine 215 along withthe enrollment data sent from the depository 210.

While these factors may generally be determined in advance of anyindividual authentication instance, they still have an effect on eachauthentication instance which uses that particular technique ofauthentication for that user. Furthermore, although the values maychange over time (e.g., if the user re-enrolls in a more reliablefashion), they are not dependent on the authentication data itself. Bycontrast, the reliability factors associated with a single specificinstance's data may vary on each occasion. These factors, as discussedbelow, must be evaluated for each new authentication in order togenerate reliability scores in step 1615.

The reliability of the authentication data reflects the match betweenthe data provided by the user in a particular authentication instanceand the data provided during the authentication enrollment. This is thefundamental question of whether the authentication data matches theenrollment data for the individual the user is claiming to be. Normally,when the data do not match, the user is considered to not besuccessfully authenticated, and the authentication fails. The manner inwhich this is evaluated may change depending on the authenticationtechnique used. The comparison of such data is performed by thecomparator 515 function of the authentication engine 215 as shown inFIG. 5.

For instance, matches of passwords are generally evaluated in a binaryfashion. In other words, a password is either a perfect match, or afailed match. It is usually not desirable to accept as even a partialmatch a password which is close to the correct password if it is notexactly correct. Therefore, when evaluating a password authentication,the reliability of the authentication returned by the comparator 515 istypically either 100% (correct) or 0% (wrong), with no possibility ofintermediate values.

Similar rules to those for passwords are generally applied to tokenbased authentication methods, such as smart cards. This is becausehaving a smart card which has a similar identifier or which is similarto the correct one, is still just as wrong as having any other incorrecttoken. Therefore tokens tend also to be binary authenticators: a usereither has the right token, or he doesn't.

However, certain types of authentication data, such as questionnairesand biometrics, are generally not binary authenticators. For example, afingerprint may match a reference fingerprint to varying degrees. Tosome extent, this may be due to variations in the quality of the datacaptured either during the initial enrollment or in subsequentauthentications. (A fingerprint may be smudged or a person may have astill healing scar or burn on a particular finger.) In other instancesthe data may match less than perfectly because the information itself issomewhat variable and based upon pattern matching. (A voice analysis mayseem close but not quite right because of background noise, or theacoustics of the environment in which the voice is recorded, or becausethe person has a cold.) Finally, in situations where large amounts ofdata are being compared, it may simply be the case that much of the datamatches well, but some doesn't. (A ten-question questionnaire may haveresulted in eight correct answers to personal questions, but twoincorrect answers.) For any of these reasons, the match between theenrollment data and the data for a particular authentication instancemay be desirably assigned a partial match value by the comparator 515.In this way, the fingerprint might be said to be a 85% match, the voiceprint a 65% match, and the questionnaire an 80% match, for example.

This measure (degree of match) produced by the comparator 515 is thefactor representing the basic issue of whether an authentication iscorrect or not. However, as discussed above, this is only one of thefactors which may be used in determining the reliability of a givenauthentication instance. Note also that even though a match to somepartial degree may be determined, that ultimately, it may be desirableto provide a binary result based upon a partial match. In an alternatemode of operation, it is also possible to treat partial matches asbinary, i.e. either perfect (100%) or failed (0%) matches, based uponwhether or not the degree of match passes a particular threshold levelof match. Such a process may be used to provide a simple pass/fail levelof matching for systems which would otherwise produce partial matches.Another factor to be considered in evaluating the reliability of a givenauthentication instance concerns the circumstances under which theauthentication data for this particular instance are provided. Asdiscussed above, the circumstances refer to the metadata associated witha particular authentication instance. This may include withoutlimitation such information as: the network address of theauthenticator, to the extent that it can be determined; the time of theauthentication; the mode of transmission of the authentication data(phone line, cellular, network, etc.); and the serial number of thesystem of the authenticator.

These factors can be used to produce a profile of the type ofauthentication that is normally requested by the user. Then, thisinformation can be used to assess reliability in at least two manners.One manner is to consider whether the user is requesting authenticationin a manner which is consistent with the normal profile ofauthentication by this user. If the user normally makes authenticationrequests from one network address during business days (when she is atwork) and from a different network address during evenings or weekends(when she is at home), an authentication which occurs from the homeaddress during the business day is less reliable because it is outsidethe normal authentication profile. Similarly, if the user normallyauthenticates using a fingerprint biometric and in the evenings, anauthentication which originates during the day using only a password isless reliable.

An additional way in which the circumstantial metadata can be used toevaluate the reliability of an instance of authentication is todetermine how much corroboration the circumstance provides that theauthenticator is the individual he claims to be. For instance, if theauthentication comes from a system with a serial number known to beassociated with the user, this is a good circumstantial indicator thatthe user is who they claim to be. Conversely, if the authentication iscoming from a network address which is known to be in Los Angeles whenthe user is known to reside in London, this is an indication that thisauthentication is less reliable based on its circumstances.

It is also possible that a cookie or other electronic data may be placedupon the system being used by a user when they interact with a vendorsystem or with the trust engine 110. This data is written to the storageof the system of the user and may contain an identification which may beread by a Web browser or other software on the user system. If this datais allowed to reside on the user system between sessions (a “persistentcookie’), it may be sent with the authentication data as furtherevidence of the past use of this system during authentication of aparticular user. In effect, the metadata of a given instance,particularly a persistent cookie, may form a sort of token basedauthenticator itself.

Once the appropriate reliability factors based on the technique and dataof the authentication instance are generated as described above in steps1610 and 1615 respectively, they are used to produce an overallreliability for the authentication instance provided in step 1620. Onemeans of doing this is simply to express each reliability as apercentage and then to multiply them together. For example, suppose theauthentication data is being sent in from a network address known to bethe user's home computer completely in accordance with the user's pastauthentication profile (100%), and the technique being used isfingerprint identification (97%), and the initial finger print data wasregistered through the user's employer with the trust engine 110 (90%),and the match between the authentication data and the originalfingerprint template in the enrollment data is very good (99%). Theoverall reliability of this authentication instance could then becalculated as the product of these reliabilities: 100%*97%*90%*99%=86.4%reliability.

This calculated reliability represents the reliability of one singleinstance of authentication. The overall reliability of a singleauthentication instance may also be calculated using techniques whichtreat the different reliability factors differently, for example byusing formulas where different weights are assigned to each reliabilityfactor. Furthermore, those of skill in the art will recognize that theactual values used may represent values other than percentages and mayuse non-arithmetic systems. One embodiment may include a module used byan authentication requestor to set the weights for each factor and thealgorithms used in establishing the overall reliability of theauthentication instance.

The authentication engine 215 may use the above techniques andvariations thereof to determine the reliability of a singleauthentication instance, indicated as step 1620. However, it may beuseful in many authentication situations for multiple authenticationinstances to be provided at the same time. For example, while attemptingto authenticate himself using the system of the present invention, auser may provide a user identification, fingerprint authentication data,a smart card, and a password. In such a case, three independentauthentication instances are being provided to the trust engine 110 forevaluation. Proceeding to step 1825, if the authentication engine 215determines that the data provided by the user includes more than oneauthentication instance, then each instance in turn will be selected asshown in step 1830 and evaluated as described above in steps 1610, 1615and 1620.

Note that many of the reliability factors discussed may vary from one ofthese instances to another. For instance, the inherent reliability ofthese techniques is likely to be different, as well as the degree ofmatch provided between the authentication data and the enrollment data.Furthermore, the user may have provided enrollment data at differenttimes and under different circumstances for each of these techniques,providing different enrollment reliabilities for each of these instancesas well. Finally, even though the circumstances under which the data foreach of these instances is being submitted is the same, the use of suchtechniques may each fit the profile of the user differently, and so maybe assigned different circumstantial reliabilities. (For example, theuser may normally use their password and fingerprint, but not theirsmart card.)

As a result, the final reliability for each of these authenticationinstances may be different from one another. However, by using multipleinstances together, the overall confidence level for the authenticationwill tend to increase.

Once the authentication engine has performed steps 1610 through 1620 forall of the authentication instances provided in the authentication data,the reliability of each instance is used in step 1635 to evaluate theoverall authentication confidence level. This process of combining theindividual authentication instance reliabilities into the authenticationconfidence level may be modeled by various methods relating theindividual reliabilities produced, and may also address the particularinteraction between some of these authentication techniques. (Forexample, multiple knowledge-based systems such as passwords may produceless confidence than a single password and even a fairly weak biometric,such as a basic voice analysis.)

One means in which the authentication engine 215 may combine thereliabilities of multiple concurrent authentication instances togenerate a final confidence level is to multiply the unreliability ofeach instance to arrive at a total unreliability. The unreliability isgenerally the complementary percentage of the reliability. For example,a technique which is 84% reliable is 16% unreliable. The threeauthentication instances described above (fingerprint, smart card,password) which produce reliabilities of 86%, 75%, and 72% would havecorresponding unreliabilities of (100-86)%, (100-75)% and (100.72)%, or14%, 25%, and 28%, respectively. By multiplying these unreliabilities,we get a cumulative unreliability of 14%*25%*28%=0.98% unreliability,which corresponds to a reliability of 99.02%.

In an additional mode of operation, additional factors and heuristics530 may be applied within the authentication engine 215 to account forthe interdependence of various authentication techniques. For example,if someone has unauthorized access to a particular home computer, theyprobably have access to the phone line at that address as well.Therefore, authenticating based on an originating phone number as wellas upon the serial number of the authenticating system does not add muchto the overall confidence in the authentication. However, knowledgebased authentication is largely independent of token basedauthentication (i.e. if someone steals your cellular phone or keys, theyare no more likely to know your PIN or password than if they hadn't).

Furthermore, different vendors or other authentication requestors maywish to weigh different aspects of the authentication differently. Thismay include the use of separate weighing factors or algorithms used incalculating the reliability of individual instances as well as the useof different means to evaluate authentication events with multipleinstances.

For instance, vendors for certain types of transactions, for instancecorporate email systems, may desire to authenticate primarily based uponheuristics and other circumstantial data by default. Therefore, they mayapply high weights to factors related to the metadata and other profilerelated information associated with the circumstances surroundingauthentication events. This arrangement could be used to ease the burdenon users during normal operating hours, by not requiring more from theuser than that he be logged on to the correct machine during businesshours. However, another vendor may weigh authentications coming from aparticular technique most heavily, for instance fingerprint matching,because of a policy decision that such a technique is most suited toauthentication for the particular vendor's purposes.

Such varying weights may be defined by the authentication requestor ingenerating the authentication request and sent to the trust engine 110with the authentication request in one mode of operation. Such optionscould also be set as preferences during an initial enrollment processfor the authentication requestor and stored within the authenticationengine in another mode of operation.

Once the authentication engine 215 produces an authentication confidencelevel for the authentication data provided, this confidence level isused to complete the authentication request in step 1640, and thisinformation is forwarded from the authentication engine 215 to thetransaction engine 205 for inclusion in a message to the authenticationrequestor.

The process described above is merely exemplary, and those of skill inthe art will recognize that the steps need not be performed in the ordershown. Furthermore, certain steps, such as the evaluation of thereliability of each authentication instance provided, may be carried outin parallel with one another if circumstances permit.

In a further aspect of this invention, a method is provided toaccommodate conditions when the authentication confidence level producedby the process described above fails to meet the required trust level ofthe vendor or other party requiring the authentication. In circumstancessuch as these where a gap exists between the level of confidenceprovided and the level of trust desired, the operator of the trustengine 110 is in a position to provide opportunities for one or bothparties to provide alternate data or requirements in order to close thistrust gap. This process will be referred to as “trust arbitrage” herein.

Trust arbitrage may take place within a framework of cryptographicauthentication as described above with reference to FIGS. 10 and 11. Asshown therein, a vendor or other party will request authentication of aparticular user in association with a particular transaction. In onecircumstance, the vendor simply requests an authentication, citherpositive or negative, and after receiving appropriate data from theuser, the trust engine 110 will provide such a binary authentication. Incircumstances such as these, the degree of confidence required in orderto secure a positive authentication is determined based upon preferencesset within the trust engine 110.

However, it is also possible that the vendor may request a particularlevel of trust in order to complete a particular transaction. Thisrequired level may be included with the authentication request (e.g.,authenticate this user to 96% confidence) or may be determined by thetrust engine 110 based on other factors associated with the transaction(i.e. authenticate this user as appropriate for this transaction). Onesuch factor might be the economic value of the transaction. Fortransactions which have greater economic value, a higher degree of trustmay be required. Similarly, for transactions with high degrees of risk ahigh degree of trust may be required. Conversely, for transactions whichare either of low risk or of low value, lower trust levels may berequired by the vendor or other authentication requestor.

The process of trust arbitrage occurs between the steps of the trustengine 110 receiving the authentication data in step 1050 of FIG. 10 andthe return of an authentication result to the vendor in step 1055 ofFIG. 10. Between these steps, the process which leads to the evaluationof trust levels and the potential trust arbitrage occurs as shown inFIG. 17. In circumstances where simple binary authentication isperformed, the process shown in FIG. 17 reduces to having thetransaction engine 205 directly compare the authentication data providedwith the enrollment data for the identified user as discussed above withreference to FIG. 10, flagging any difference as a negativeauthentication.

As shown in FIG. 17, the first step after receiving the data in step1050 is for the transaction engine 205 to determine the trust levelwhich is required for a positive authentication for this particulartransaction in step 1710. This step may be performed by one of severaldifferent methods. The required trust level may be specified to thetrust engine 110 by the authentication requestor at the time when theauthentication request is made. The authentication requestor may alsoset a preference in advance which is stored within the depository 210 orother storage which is accessible by the transaction engine 205. Thispreference may then be read and used each time an authentication requestis made by this authentication requestor. The preference may also beassociated with a particular user as a security measure such that aparticular level of trust is always required in order to authenticatethat user, the user preference being stored in the depository 210 orother storage media accessible by the transaction engine 205. Therequired level may also be derived by the transaction engine 205 orauthentication engine 215 based upon information provided in theauthentication request, such as the value and risk level of thetransaction to be authenticated.

In one mode of operation, a policy management module or other softwarewhich is used when generating the authentication request is used tospecify the required degree of trust for the authentication of thetransaction. This may be used to provide a series of rules to followwhen assigning the required level of trust based upon the policies whichare specified within the policy management module. One advantageous modeof operation is for such a module to be incorporated with the web serverof a vendor in order to appropriately determine required level of trustfor transactions initiated with the vendor's web server. In this way,transaction requests from users may be assigned a required trust levelin accordance with the policies of the vendor and such information maybe forwarded to the trust engine 110 along with the authenticationrequest.

This required trust level correlates with the degree of certainty thatthe vendor wants to have that the individual authenticating is in factwho he identifies himself as. For example, if the transaction is onewhere the vendor wants a fair degree of certainty because goods arechanging hands, the vendor may require a trust level of 85%. Forsituation where the vendor is merely authenticating the user to allowhim to view members only content or exercise privileges on a chat room,the downside risk may be small enough that the vendor requires only a60% trust level. However, to enter into a production contract with avalue of tens of thousands of dollars, the vendor may require a trustlevel of 99% or more.

This required trust level represents a metric to which the user mustauthenticate himself in order to complete the transaction. If therequired trust level is 85% for example, the user must provideauthentication to the trust engine 110 sufficient for the trust engine110 to say with 85% confidence that the user is who they say they are.It is the balance between this required trust level and theauthentication confidence level which produces either a positiveauthentication (to the satisfaction of the vendor) or a possibility oftrust arbitrage.

As shown in FIG. 17, after the transaction engine 205 receives therequired trust level, it compares in step 1720 the required trust levelto the authentication confidence level which the authentication engine215 calculated for the current authentication (as discussed withreference to FIG. 16). If the authentication confidence level is higherthan the required trust level for the transaction in step 1730, then theprocess moves to step 1740 where a positive authentication for thistransaction is produced by the transaction engine 205. A message to thiseffect will then be inserted into the authentication results andreturned to the vendor by the transaction engine 205 as shown in step1055 (see FIG. 10).

However, if the authentication confidence level does not fulfill therequired trust level in step 1730, then a confidence gap exists for thecurrent authentication, and trust arbitrage is conducted in step 1750.Trust arbitrage is described more completely with reference to FIG. 18below. This process as described below takes place within thetransaction engine 205 of the trust engine 110. Because noauthentication or other cryptographic operations are needed to executetrust arbitrage (other than those required for the SSL communicationbetween the transaction engine 205 and other components), the processmay be performed outside the authentication engine 215. However, as willbe discussed below, any reevaluation of authentication data or othercryptographic or authentication events will require the transactionengine 205 to resubmit the appropriate data to the authentication engine215. Those of skill in the art will recognize that the trust arbitrageprocess could alternately be structured to take place partially orentirely within the authentication engine 215 itself.

As mentioned above, trust arbitrage is a process where the trust engine110 mediates a negotiation between the vendor and user in an attempt tosecure a positive authentication where appropriate. As shown in step1805, the transaction engine 205 first determines whether or not thecurrent situation is appropriate for trust arbitrage. This may bedetermined based upon the circumstances of the authentication, e.g.,whether this authentication has already been through multiple cycles ofarbitrage, as well as upon the preferences of either the vendor or user,as will be discussed further below.

In such circumstances where arbitrage is not possible, the processproceeds to step 1810 where the transaction engine 205 generates anegative authentication and then inserts it into the authenticationresults which are sent to the vendor in step 1055 (see FIG. 10). Onelimit which may be advantageously used to prevent authentications frompending indefinitely is to set a time-out period from the initialauthentication request. In this way, any transaction which is notpositively authenticated within the time limit is denied furtherarbitrage and negatively authenticated. Those of skill in the art willrecognize that such a time limit may vary depending upon thecircumstances of the transaction and the desires of the user and vendorLimitations may also be placed upon the number of attempts that may bemade at providing a successful authentication. Such limitations may behandled by an attempt limiter as shown in FIG. 5.

If arbitrage is not prohibited in step 1805, the transaction engine 205will then engage in negotiation with one or both of the transactingparties. The transaction engine 205 may send a message to the userrequesting some form of additional authentication in order to boost theauthentication confidence level produced as shown in step 1820. In thesimplest form, this may simply indicates that authentication wasinsufficient. A request to produce one or more additional authenticationinstances to improve the overall confidence level of the authenticationmay also be sent.

If the user provides some additional authentication instances in step1825, then the transaction engine 205 15 adds these authenticationinstances to the authentication data for the transaction and forwards itto the authentication engine 215 as shown in step 1015 (see FIG. 10),and the authentication is reevaluated based upon both the pre-existingauthentication instances for this transaction and the newly providedauthentication instances.

An additional type of authentication may be a request from the trustengine 110 to make some form of person-to-person contact between thetrust engine 110 operator (or a trusted associate) and the user, forexample, by phone call. This phone call or other non-computerauthentication can be used to provide personal contact with theindividual and also to conduct some form of questionnaire basedauthentication. This also may give the opportunity to verify anoriginating telephone number and potentially a voice analysis of theuser when he calls in. Even if no additional authentication data can beprovided, the additional context associated with the user's phone numbermay improve the reliability of the authentication context. Any reviseddata or circumstances based upon this phone call are fed into the trustengine 110 for use in consideration of the authentication request.

Additionally, in step 1820 the trust engine 110 may provide anopportunity for the user to purchase insurance, effectively buying amore confident authentication. The operator of the trust engine 110 may,at times, only want to make such an option available if the confidencelevel of the authentication is above a certain threshold to begin with.In effect, this user side insurance is a way for the trust engine 110 tovouch for the user when the authentication meets the normal requiredtrust level of the trust engine 110 for authentication, but does notmeet the required trust level of the vendor for this transaction. Inthis way, the user may still successfully authenticate to a very highlevel as may be required by the vendor, even though he only hasauthentication instances which produce confidence sufficient for thetrust engine 110.

This function of the trust engine 110 allows the trust engine 110 tovouch for someone who is authenticated to the satisfaction of the trustengine 110, but not of the vendor. This is analogous to the functionperformed by a notary in adding his signature to a document in order toindicate to someone reading the document at a later time that the personwhose signature appears on the document is in fact the person who signedit. The signature of the notary testifies to the act of signing by theuser. In the same way, the trust engine is providing an indication thatthe person transacting is who they say they are.

However, because the trust engine 110 is artificially boosting the levelof confidence provided by the user, there is a greater risk to the trustengine 110 operator, since the user is not actually meeting the requiredtrust level of the vendor. The cost of the insurance is designed tooffset the risk of a false positive authentication to the trust engine110 (who may be effectively notarizing the authentications of the user).The user pays the trust engine 110 operator to take the risk ofauthenticating to a higher level of confidence than has actually beenprovided.

Because such an insurance system allows someone to effectively buy ahigher confidence rating from the trust engine 110, both vendors andusers may wish to prevent the use of user side insurance in certaintransactions. Vendors may wish to limit positive authentications tocircumstances where they know that actual authentication data supportsthe degree of confidence which they require and so may indicate to thetrust engine 110 that user side insurance is not to be allowed.Similarly, to protect his online identity, a user may wish to preventthe use of user side insurance on his account, or may wish to limit itsuse to situations where the authentication confidence level without theinsurance is higher than a certain limit. This may be used as a securitymeasure to prevent someone from overhearing a password or stealing asmart card and using them to falsely authenticate to a low level ofconfidence, and then purchasing insurance to produce a very high levelof (false) confidence. These factors may be evaluated in determiningwhether user side insurance is allowed.

If user purchases insurance in step 1840, then the authenticationconfidence level is adjusted based upon the insurance purchased in step1845, and the authentication confidence level and required trust levelare again compared in step 1730 (see FIG. 17). The process continuesfrom there, and may lead to either a positive authentication in step1740 (see FIG. 17), or back into the trust arbitrage process in step1750 for either further arbitrage (if allowed) or a negativeauthentication in step 1810 if further arbitrage is prohibited.

In addition to sending a message to the user in step 1820, thetransaction engine 205 may also send a message to the vendor in step1830 which indicates that a pending authentication is currently belowthe required trust level. The message may also offer various options onhow to proceed to the vendor. One of these options is to simply informthe vendor of what the current authentication confidence level is andask if the vendor wishes to maintain their current unfulfilled requiredtrust level. This may be beneficial because in some cases, the vendormay have independent means for authenticating the transaction or mayhave been using a default set of requirements which generally result ina higher required level being initially specified than is actuallyneeded for the particular transaction at hand

For instance, it may be standard practice that all incoming purchaseorder transactions with the vendor are expected to meet a 98% trustlevel. However, if an order was recently discussed by phone between thevendor and a long-standing customer, and immediately thereafter thetransaction is authenticated, but only to a 93% confidence level, thevendor may wish to simply lower the acceptance threshold for thistransaction, because the phone call effectively provides additionalauthentication to the vendor. In certain circumstances, the vendor maybe willing to lower their required trust level, but not all the way tothe level of the current authentication confidence. For instance, thevendor in the above example might consider that the phone call prior tothe order might merit a 4% reduction in the degree of trust needed;however, this is still greater than the 93% confidence produced by theuser.

If the vendor does adjust their required trust level in step 1835, thenthe authentication confidence level produced by the authentication andthe required trust level are compared in step 1730 (see FIG. 17). If theconfidence level now exceeds the required trust level, a positiveauthentication may be generated in the transaction engine 205 in step1740 (see FIG. 17). If not, further arbitrage may be attempted asdiscussed above if it is permitted.

In addition to requesting an adjustment to the required trust level, thetransaction engine 205 may also offer vendor side insurance to thevendor requesting the authentication. This insurance serves a similarpurpose to that described above for the user side insurance. Here,however, rather than the cost corresponding to the risk being taken bythe trust engine 110 in authenticating above the actual authenticationconfidence level produced, the cost of the insurance corresponds to therisk being taken by the vendor in accepting a lower trust level in theauthentication.

Instead of just lowering their actual required trust level, the vendorhas the option of purchasing insurance to protect itself from theadditional risk associated with a lower level of trust in theauthentication of the user. As described above, it may be advantageousfor the vendor to only consider purchasing such insurance to cover thetrust gap in conditions where the existing authentication is alreadyabove a certain threshold.

The availability of such vendor side insurance allows the vendor theoption to either: lower his trust requirement directly at no additionalcost to himself, bearing the risk of a false authentication himself(based on the lower trust level required); or, buying insurance for thetrust gap between the authentication confidence level and hisrequirement, with the trust engine 110 operator bearing the risk of thelower confidence level which has been provided. By purchasing theinsurance, the vendor effectively keeps his high trust levelrequirement, because the risk of a false authentication is shifted tothe trust engine 110 operator.

If the vendor purchases insurance in step 1840, the authenticationconfidence level and required trust levels are compared in step 1730(see FIG. 17), and the process continues as described above.

Note that it is also possible that both the user and the vendor respondto messages from the trust engine 110. Those of skill in the art willrecognize that there are multiple ways in which such situations can behandled. One advantageous mode of handling the possibility of multipleresponses is simply to treat the responses in a first-come, first-servedmanner. For example, if the vendor responds with a lowered requiredtrust level and immediately thereafter the user also purchases insuranceto raise his authentication level, the authentication is firstreevaluated based upon the lowered trust requirement from the vendor. Ifthe authentication is now positive, the user's insurance purchase isignored. In another advantageous mode of operation, the user might onlybe charged for the level of insurance required to meet the new, loweredtrust requirement of the vendor (if a trust gap remained even with thelowered vendor trust requirement).

If no response from either party is received during the trust arbitrageprocess at step 1850 within the time limit set for the authentication,the arbitrage is reevaluated in step 1805. This effectively begins thearbitrage process again. If the time limit was final or othercircumstances prevent further arbitrage in step 1805, a negativeauthentication is generated by the transaction engine 205 in step 1810and returned to the vendor in step 1055 (see FIG. 10). If not, newmessages may be sent to the user and vendor, and the process may berepeated as desired.

Note that for certain types of transactions, for instance, digitallysigning documents which are not part of a transaction, there may notnecessarily be a vendor or other third party; therefore the transactionis primarily between the user and the trust engine 110. In circumstancessuch as these, the trust engine 110 will have its own required trustlevel which must be satisfied in order to generate a positiveauthentication. However, in such circumstances, it will often not bedesirable for the trust engine 110 to offer insurance to the user inorder for him to raise the confidence of his own signature.

The process described above and shown in FIGS. 16-18 may be carried outusing various communications modes as described above with reference tothe trust engine 110. For instance, the messages may be web-based andsent using SSL connections between the trust engine 110 and appletsdownloaded in real time to browsers running on the user or vendorsystems. In an alternate mode of operation, certain dedicatedapplications may be in use by the user and vendor which facilitate sucharbitrage and insurance transactions. In another alternate mode ofoperation, secure email operations may be used to mediate the arbitragedescribed above, thereby allowing deferred evaluations and batchprocessing of authentications. Those of skill in the art will recognizethat different communications modes may be used as are appropriate forthe circumstances and authentication requirements of the vendor.

The following description with reference to FIG. 19 describes a sampletransaction which integrates the various aspects of the presentinvention as described above. This example illustrates the overallprocess between a user and a vendor as mediates by the trust engine 110.Although the various steps and components as described in detail abovemay be used to carry out the following transaction, the processillustrated focuses on the interaction between the trust engine 110,user and vendor.

The transaction begins when the user, while viewing web pages online,fills out an order form on the web site of the vendor in step 1900. Theuser wishes to submit this order form to the vendor, signed with hisdigital signature. In order to do this, the user submits the order formwith his request for a signature to the trust engine 110 in step 1905.The user will also provide authentication data which will be used asdescribed above to authenticate his identity.

In step 1910 the authentication data is compared to the enrollment databy the trust engine 110 as discussed above, and if a positiveauthentication is produced, the hash of the order form, signed with theprivate key of the user, is forwarded to the vendor along with the orderform itself.

The vendor receives the signed faun in step 1915, and then the vendorwill generate an invoice or other contract related to the purchase to bemade in step 1920. This contract is sent back to the user with a requestfor a signature in step 1925. The vendor also sends an authenticationrequest for this contract transaction to the trust engine 110 in step1930 including a hash of the contract which will be signed by bothparties. To allow the contract to be digitally signed by both parties,the vendor also includes authentication data for itself so that thevendor's signature upon the contract can later be verified if necessary.

As discussed above, the trust engine 110 then verifies theauthentication data provided by the vendor to confirm the vendor'sidentity, and if the data produces a positive authentication in step1935, continues with step 1955 when the data is received from the user.If the vendor's authentication data does not match the enrollment dataof the vendor to the desired degree, a message is returned to the vendorrequesting further authentication. Trust arbitrage may be performed hereif necessary, as described above, in order for the vendor tosuccessfully authenticate itself to the trust engine 110.

When the user receives the contract in step 1940, he reviews it,generates authentication data to sign it if it is acceptable in step1945, and then sends a hash of the contract and his authentication datato the trust engine 110 in step 1950. The trust engine 110 verifies theauthentication data in step 1955 and if the authentication is good,proceeds to process the contract as described below. As discussed abovewith reference to FIGS. 17 and 18, trust arbitrage may be performed asappropriate to close any trust gap which exists between theauthentication confidence level and the required authentication levelfor the transaction.

The trust engine 110 signs the hash of the contract with the user'sprivate key, and sends this signed hash to the vendor in step 1960,signing the complete message on its own behalf, i.e. including a hash ofthe complete message (including the user's signature) encrypted with theprivate key 510 of the trust engine 110. This message is received by thevendor in step 1965. The message represents a signed contract (hash ofcontract encrypted using user's private key) and a receipt from thetrust engine 110 (the hash of the message including the signed contract,encrypted using the trust engine 110's private key).

The trust engine 110 similarly prepares a hash of the contract with thevendor's private key in step 1970, and forwards this to the user, signedby the trust engine 110. In this way, the user also receives a copy ofthe contract, signed by the vendor, as well as a receipt, signed by thetrust engine 110, for delivery of the signed contract in step 1975.

In addition to the foregoing, an additional aspect of the inventionprovides a cryptographic Service Provider Module (SPM) which may beavailable to a client side application as a means to access functionsprovided by the trust engine 110 described above. One advantageous wayto provide such a service is for the cryptographic SPM is to mediatecommunications between a third party Application Programming Interface(API) and a trust engine 110 which is accessible via a network or otherremote connection. A sample cryptographic SPM is described below withreference to FIG. 20.

For example, on a typical system, a number of API's are available toprogrammers. Each API provides a set of function calls which may be madeby an application 2000 running upon the system. Examples of API's whichprovide programming interfaces suitable for cryptographic functions,authentication functions, and other security function include theCryptographic API (CAPI) 2010 provided by Microsoft with its Windowsoperating systems, and the Common Data Security Architecture (CDSA),sponsored by 113M, Intel and other members of the Open Group. CAPI willbe used as an exemplary security API in the discussion that follows.However, the cryptographic SPM described could be used with CDSA orother security API's as are known in the art.

This API is used by a user system 105 or vendor system 120 when a callis made for a cryptographic function. Included among these functions maybe requests associated with performing various cryptographic operations,such as encrypting a document with a particular key, signing a document,requesting a digital certificate, verifying a signature upon a signeddocument, and such other cryptographic functions as are described aboveor known to those of skill in the art.

Such cryptographic functions are normally performed locally to thesystem upon which CAPI 2010 is located. This is because generally thefunctions called require the use of either resources of the local usersystem 105, such as a fingerprint reader, or software functions whichare programmed using libraries which are executed on the local machine.Access to these local resources is normally provided by one or moreService Provider Modules (SPM's) 2015, 2020 as referred to above whichprovide resources with which the cryptographic functions are carriedout. Such SPM's may include software libraries 2015 to performencrypting or decrypting operations, or drivers and applications 2020which are capable of accessing specialized hardware 2025, such asbiometric scanning devices. In much the way that CAPI 2010 providesfunctions which may be used by an application 2000 of the system 105,the SPM's 2015, 2020 provide CAPI with access to the lower levelfunctions and resources associated with the available services upon thesystem.

In accordance with the invention, it is possible to provide acryptographic SPM 2030 which is capable of accessing the cryptographicfunctions provided by the trust engine 110 and making these functionsavailable to an application 2000 through CAPI 2010. Unlike embodimentswhere CAPI 2010 is only able to access resources which are locallyavailable through SPM's 2015, 2020, a cryptographic SPM 2030 asdescribed herein would be able to submit requests for cryptographicoperations to a remotely-located, network-accessible trust engine 110 inorder to perform the operations desired.

For instance, if an application 2000 has a need for a cryptographicoperation, such as signing a document, the application 2000 makes afunction call to the appropriate CAP12010 function. CAPI 2010 in turnwill execute this function, making use of the resources which are madeavailable to it by the SPM's 2015, 2020 and the cryptographic SPM 2030.In the case of a digital signature function, the cryptographic SPM 2030will generate an appropriate request which will be sent to the trustengine 110 across the communication link 125.

The operations which occur between the cryptographic SPM 2030 and thetrust engine 110 are the same operations that would be possible betweenany other system and the trust engine 110. However, these functions areeffectively made available to a user system 105 through CAPI 2010 suchthat they appear to be locally available upon the user system 105itself. However, unlike ordinary SPM's 2015, 2020, the functions arebeing carried out on the remote trust engine 110 and the results relayedto the cryptographic SPM 2030 in response to appropriate requests acrossthe communication link 125.

This cryptographic SPM 2030 makes a number of operations available tothe user system 105 or a vendor system 120 which might not otherwise beavailable. These functions include without limitation: encryption anddecryption of documents; issuance of digital certificates; digitalsigning of documents; verification of digital signatures; and such otheroperations as will be apparent to those of skill in the art.

Additionally, other combinations, admissions, substitutions andmodifications will be apparent to the skilled artisan in view of thedisclosure herein. Accordingly, the present invention is not intended tobe limited by the reaction of the preferred embodiments but is to bedefined by a reference to the appended claims.

What is claimed is:
 1. A method of performing graded authentication of auser wherein the method obtains and evaluates circumstantial dataassociated with an authentication attempt, the method comprising:obtaining user data from a user during an authentication attempt;obtaining circumstantial data associated with the authenticationattempt; and determining a level of trust associated with theauthentication attempt based on the comparison of the circumstantialdata with previously stored data.
 2. A method as in claim 1 wherein saidact of determining the level of trust associated with the authenticationattempt is further based on the comparison of the user data withpreviously stored data.
 3. A method as in claim 1 wherein the previouslystored data comprises in part a historical record of the circumstantialdata obtained during previous successful authentications for the user.4. A method as in claim 1 wherein the circumstantial data comprises anidentification associated with the system from which the user data isobtained.
 5. A method as in claim 4 wherein the identification comprisesa processor serial number.
 6. A method as in claim 1 wherein thecircumstantial data comprises an identification associated with thenetwork location of the system from which the user data is obtained. 7.A method as in claim 6 wherein the identification comprises an IPaddress.
 8. A method as in claim 1 wherein the circumstantial datacomprises a time stamp associated with the time at which the user datawas obtained.
 9. A method as in claim 1 wherein the circumstantial datacomprises an identifier representing the medium over which the user datais obtained.
 10. A method as in claim 1 wherein the circumstantial datarepresents more than one circumstantial aspect of the authenticationattempt.
 11. A method as in claim 10 wherein the circumstantial datacomprises a time stamp associated with the time at which the user datawas obtained and an identification associated with the network locationof the system from which the user data is obtained.
 12. A system forgraded authentication comprising user data obtained from a user duringat least one previously successful authentication attempt,circumstantial data associated with the at least one previouslysuccessful authentication attempt, and a trust engine which generates alevel of trust associated with a current authentication attempt based onthe comparison of circumstantial data associated with the currentauthentication attempt with the circumstantial data associated with theat least one previously successful authentication attempt.
 13. A systemas in claim 12 wherein the user data represents an intent to assent to atransaction.
 14. A system as in claim 12 wherein the circumstantial datarepresents a network address associated with the authentication attempt.15. A system as in claim 12 wherein the circumstantial data represents atime stamp associated with the authentication attempt.
 16. A system asin claim 12 wherein the level of trust is also based upon the comparisonof the user data to previously stored user data.
 17. A method forauthenticating a user comprising: obtaining user data associated with anauthentication operation; obtaining metadata related to theauthentication operation; comparing the metadata with previously storeddata; and determining a level of trust associated with theauthentication operation.
 18. A method as in claim 17 wherein the userdata associated with the authentication operation represents the intentof a user to assent to a transaction.
 19. A method as in claim 18wherein the metadata related to the authentication operation are madeavailable at a later time to contest a repudiation of the authenticationoperation by the user.
 20. A method as in claim 17 wherein the act ofdetermining a level of trust associated with the authenticationoperation comprises assigning a percentage to the authenticationoperation which represents the degree of confidence in theauthentication of the user.
 21. A method as in claim 17 furthercomprising determining an intermediate level of trust associated withthe metadata based upon the comparison of the metadata with previouslystored data.
 22. A method as in claim 21 wherein the act of determiningan intermediate level of trust comprises assigning a percentage to themetadata which represents the degree of correspondence between themetadata and the previously stored data.
 23. A method as in claim 22wherein the act of determining a level of trust associated with theauthentication operation comprises multiplying the percentagerepresenting the intermediate level of trust and a percentage whichrepresents a degree of correspondence between the user data and thepreviously stored data.
 24. A method as in claim 23 wherein additionalfactors are used to weight the percentage representing the intermediatelevel of trust and the percentage which represents the degree ofcorrespondence between the user data and the previously stored datadifferently.
 25. A method for authenticating a user comprising:obtaining user data associated with an authentication operation;obtaining metadata related to the authentication operation; anddetermining a level of trust associated with the authenticationoperation based on the metadata.
 26. A method as in claim 25 wherein theact of determining a level of trust compares the metadata withpreviously stored data.
 27. A method as in claim 25 further comprisingproviding the user with a plurality of authentication techniques whichmay be used to generate the user data.
 28. A method as in claim 27wherein the user data is generated using more than one of the pluralityof authentication techniques.
 29. A method as in claim 28 wherein theuser data generated using each authentication technique is compared witha different portion of a set of previously stored data.
 30. A method forgrading an authentication operation that relies on a variable set ofauthentication techniques to obtain authentication data, the methodcomprising: defining the reliability of a set of authenticationtechniques that may be used in an authentication operation; receivingauthentication data during an authentication operation, saidauthentication data generated using a subset of the authenticationtechniques; determining the acceptability of the authentication datagenerated by each of the subset of authentication techniques; anddefining the level of trust of the authentication operation based uponthe acceptability of the authentication data and based upon thereliability of the authentication techniques used in generating theauthentication data.
 31. The method of claim 30 wherein the act ofdetermining the acceptability involves comparing the authentication datawith previously stored enrollment data.
 32. The method of claim 31wherein the act of defining the reliability of a set of authenticationtechniques is based upon a set of circumstances associated with thepreviously stored enrollment data.
 33. The method of claim 30 whereinthe act of defining the reliability of a set of authenticationtechniques is based upon the circumstances associated with thegeneration of the authentication data.
 34. An apparatus for evaluatingan authentication attempt comprising: reliability data associated with aset of authentication techniques that may be used in an authenticationattempt; a plurality of authentication instances generated using asubset of the authentication techniques; and a trust engine whichdetermines a level of match associated with each authentication instanceand assigns a level of trust for the authentication attempt based uponthe level of match associated with each authentication instance and thereliability of the technique used in each authentication instance. 35.An apparatus as in claim 34 further comprising a required level of trustassociated with the authentication attempt.
 36. An apparatus as in claim34 wherein the trust engine further assigns a result for theauthentication based upon a comparison of the level of trust associatedwith the authentication attempt and the required level of trust.
 37. Anapparatus as in claim 34 wherein the required level of trust isdetermined by the trust engine based upon the risk associated with asuccessful authentication.
 38. A method for grading an authenticationattempt comprising: defining the reliability of a set of authenticationtechniques that may be used in an authentication attempt; receiving aplurality of authentication instances generated using a subset of theauthentication techniques; determining a level of match associated witheach authentication instance; and defining a level of trust of theauthentication attempt based upon the level of match associated witheach authentication instance and based upon the reliability of thetechnique used in each authentication instance.
 39. A method as in claim38 further comprising defining a required level of trust for theauthentication attempt.
 40. A method as in claim 39 further comprisingassigning an authentication result to the authentication attempt basedon a comparison of the level of trust for the authentication attempt anda required level of trust of the authentication attempt.
 41. A method asin claim 39 wherein the required level of trust for the authenticationattempt is based upon the value associated with a successfulauthentication.
 42. A method as in claim 39 wherein the required levelof trust for the authentication attempt is based upon the riskassociated with a successful authentication.